1-Pentanethiol was theremally decomposed in a quartz tube utilizing a flow method. The apparatus and techniques used in this investigation have been described in a previous publication. The conditions (300-500 degrees with exposure times of 10 to 120 seconds) employed in this study resulted in decompositions ranging from 0.2 to 87%. The predominant sulfur containing decomposition product was hydrogen sulfude. Small amounts of sulfides and residual sulfur were also produced. The decomposition, as postulated, proceeds by way of an intramolecular splitting of 1-pentanethiol to produce pentene and hydrogen sulfide.