What Is Lyocell? TENCEL, How It's Made, and Lyocell vs Cotton

Under US labeling rules, lyocell isn't its own fiber. The Federal Trade Commission files it as a kind of rayon. The FTC's textile rule defines rayon as regenerated cellulose, then says that when the cellulose comes out of an organic solution with no chemical intermediates formed, "the term lyocell may be used as a generic description of the fiber."

So the same family as viscose and modal. That surprises a lot of people who see "TENCEL Lyocell" on a tag and assume it's a plant fiber like cotton or linen. It isn't. It's usually wood pulp that has been dissolved and spun back into a fiber. What makes it different from viscose is how that dissolving happens, and that difference is the reason lyocell gets so much attention.

What is lyocell?

Lyocell is a regenerated cellulose fiber. Cellulose is the stuff plants are built from. To make lyocell, a manufacturer takes dissolving pulp (usually from wood), dissolves it, pushes the solution through tiny holes, and lets it set into fibers.

According to Lenzing, the Austrian company that makes TENCEL, its lyocell is made by dissolving cellulose in an organic solvent called N-methylmorpholine-N-oxide, or NMMO. The pulp is mixed with water and NMMO, the water is removed until the cellulose dissolves, and the thick solution is filtered and spun. Lenzing says the raw material can be wood or other cellulose sources such as cotton scraps.

Lenzing calls lyocell the third generation of regenerated cellulose fibers, after viscose and modal, with commercial production going back roughly 30 years.

What is TENCEL?

TENCEL is a brand, not a different fiber. It's Lenzing's trademark for its lyocell and modal. "Lyocell" is the generic name any manufacturer can use. That's why tags say "TENCEL™ Lyocell": the brand plus the generic fiber name the label rules require.

So when someone asks whether "TENCEL lyocell" is better than plain "lyocell," the honest answer is that it's the same type of fiber, and the difference is who made it and what they can document. Lenzing claims its TENCEL Lyocell and Modal are made with at least 50% less carbon emissions and water use than generic lyocell and modal, based on the Higg Materials Sustainability Index. That's Lenzing's own comparison, but it does cite a method. An unbranded lyocell tag tells you nothing about the mill, so you can't compare it either way.

Lenzing also says the wood for all TENCEL Lyocell and Modal comes from FSC or PEFC certified or controlled sources, and that the fibers carry a tracer so they can be identified in a finished garment. Its own fine print says those certifications apply to the fiber only, not to the finished product.

Lyocell vs viscose: what's actually different?

Both start as dissolving pulp. The difference is the chemistry in the middle.

For viscose, Lenzing describes steeping pulp in sodium hydroxide and then reacting it with carbon disulfide before it can dissolve. Lyocell skips that reaction. The cellulose dissolves directly in NMMO, which is exactly what the FTC definition is pointing at when it says "no chemical intermediates are formed."

The other headline is solvent recovery. Lenzing says it recovers about 99.8% of the NMMO and feeds it back into the process.

We'd add one caveat. Those recovery numbers describe Lenzing's plants. A generic lyocell from another mill could be run very differently, and the tag won't say.

If you want the viscose side in more detail, we covered it in is viscose safe?, and the wider family, cupro included, in our post on regenerated cellulose fiber. Modal, the closest cousin, has its own explainer.

Lyocell vs cotton

This is the comparison most people are really making when they're shopping for a tee or sheets. Here's how they line up on the things we could find real numbers for.

Moisture. A 2024 study from the University of Zagreb knitted socks from lyocell, viscose and cotton under the same conditions, and the lyocell and viscose socks absorbed moisture and let air through better than the cotton ones.

Strength. The same researchers note that lyocell keeps up to 85% of its dry strength when wet, which is more than other man-made cellulose fibers manage. So lyocell doesn't share viscose's big drop in strength when it's wet.

Wear. Here cotton wins, at least in one test. In that Zagreb study, socks made mostly of lyocell lasted fewer abrasion rubs than cotton socks. After five washes, the cotton socks held out to 30,000 to 45,000 rubs, and the researchers rated lyocell and viscose socks "significantly lower." Lyocell's strong yarn didn't save it, because of something called fibrillation (more on that below). The lyocell socks did resist pilling better than cotton in the unwashed test.

End of life. Lenzing says its standard lyocell fibers are certified by TÜV Austria as biodegradable in soil, freshwater and marine environments and compostable at home. Two catches from Lenzing's own page: that applies to the fiber, so dyes, finishes and blend partners matter, and the claim is listed as not applicable in California or France. A cotton and polyester blend, or lyocell with spandex, is a different story. We get into the polyester side in polyester vs cotton.

So which is better? For a hot-weather shirt or bedding, lyocell has real advantages in how it handles moisture. For something that gets scrubbed against shoes all day, like socks, cotton held up better in the one study we found.

Why lyocell gets fuzzy in the wash

Lyocell's long, highly ordered molecules are what make it strong. They're also why it can split. Researchers at Aalto University note that lyocell-type fibers "often have high fibrillation tendency in the wet, swollen state or under high mechanical abrasion conditions." Tiny fibrils peel off the surface and the fabric picks up a fuzzy, peach skin look. Viscose and modal barely do this.

If you have a cotton and TENCEL tee you love and want it to last, this is the part that matters. Wet rubbing is what causes the damage, so the gentler and less crowded the wash, the better. Following the care label on that specific garment is the practical move.

Mills also manage this before the garment reaches you. Lyocell can be crosslinked, a chemical treatment that ties the fibrils together, and in the Aalto tests the well-crosslinked fibers showed "negligible fibrillation tendency." Your label won't tell you whether the fiber was crosslinked or which finishes were used. If that matters to you, it's a fair question to ask the brand.

Is lyocell a good choice?

It depends on what you're comparing it to and what you can verify.

Next to conventional viscose, lyocell avoids the carbon disulfide step, and Lenzing documents a closed solvent loop. Next to polyester, it's made from wood cellulose rather than plastic. Next to cotton, it's a trade: cooler and drier feeling, often less hard-wearing on high-friction items.

What a tag can't tell you is the finishing. Lenzing lists an OEKO-TEX Standard 100 certificate for its fibers, but a fiber certificate doesn't cover the dyes and finishes added later in the supply chain. A certificate on the finished garment tells you more. Our lyocell material guide shows how we score the fiber on its own.

How to read a lyocell label

• "TENCEL™ Lyocell" means Lenzing made the fiber. You can check the brand's claims on tencel.com.
• "Lyocell" on its own means any manufacturer. That isn't automatically worse. It just means less is documented.
• "Rayon" or "viscose" usually means the older process, not lyocell. See our post on bamboo viscose for how "bamboo" gets used on those labels.
• Check the blend. A lot of lyocell shirts are blended with cotton, and leggings or tanks often add elastane or nylon. The percentages tell you more than the hero fiber in the product name.

Most of the time you're looking at all this on a product page, not in a store holding the tag. That's the part Greener Closet helps with: it pulls the fiber composition from the listing and scores it while you browse. We can only score what the listing discloses, so if a brand just says "TENCEL" without percentages, that's worth a closer look before you buy.