As the global textile industry moves toward sustainable, bio-based materials, a regenerated cellulosic fiber lyocell-has emerged as a premier choice for high-performance apparel and industrial textiles. Beyond its well-documented ecological advantages, such as its closed-loop production process and biodegradability, the safety profile of lyocell is of critical importance, particularly in sectors where fire resistance is non-negotiable. Evaluating lyocell under ISO 15025, which specifies the procedure for determining the limited flame spread of vertically oriented textile fabrics, provides essential insights into how this fibre behaves in high-risk environments.