Degradation route studies show that hexythiazox is rapidly metabolised in soil under aerobic conditions, initially to several metabolites and ultimately to CO2 and soil bound residues. The first step in the degradation route is the hydroxylation of the cyclohexane ring to form PT-1-4 and PT-1-8 (sum of both up to 11.4 %). These degradation products are further metabolised to PT-1-9 (up to 21.1 %) by the oxidation of the cyclohexane ring. PT-1-9 is further degraded to PT-1-2 (up to 39.5 %) by cleavage of the two C-N-bonds of the urea moiety. Hydrolysis of the amino carbonyl (carbamoyl) substituent in the thiazolidinone moiety of PT-1-2 yields PT-1-3 (up to 9.2 %). Final degradation to CO2 (up to 18.9 %) occurs probably via formation of PC-1-1 (p-chlorobenzoic acid). However, PC-1-1 was not found in the soil degradation studies. The formation of nonextractable residues (up to ca. 50 %) is another important dissipation pathway of Hexythiazox in soil. The same degradation pathway is observed under anaerobic conditions. The cyclohexane-hydroxylated degradation products of hexythiazox (comprising the isomers PT-1-4, PT-1-6 and PT-1-8) reached levels up to 14.9 % and the cyclohexane-oxylated products (comprising the isomers PT-1-5, PT-1-7, PT-1-9) reached levels up to 7.0 % under anaerobic conditions. The degradation products PT-1-2 and PT-1-3 accounted for up to 21.0 % and 3.2 %, respectively. Under realistic outdoor conditions, anaerobic conditions are unlikely to occur in soil after application of hexythiazox in apples, grapes and citrus. Under aerobic conditions none of the cyclohexane-hydroxylated compounds exceeded 2.5 %. The half-life (DT50) of hexythiazox in soil under aerobic conditions ranged from 6 days (25ºC) to 35 days (20°C) and DT90 values at 20°C ranged from 107 to 117 days. Under anaerobic conditions the degradation of hexythiazox was estimated to be slower with a DT50 value of 120 days. The DT50 values of the major metabolites of hexythiazox under aerobic conditions in soil at 20ºC ranged from 43.9 to 54.6 days for PT-1-9, from 28 to 269 days for PT-1-2 and from 16 to 35 days for PT-1-3.