The invention relates to the use of at least one compound of formula (1): R—Sn—R′  (1) wherein R and R′ are each a hydrocarbon radical containing between 1 and 12 carbon atoms and n is a whole number between 1 and 8, for maintaining the viscosity of liquid sulfur at a value lower than 60,000 mPa·s, preferably lower than 30,000 mPa·s, especially preferably lower than 10,000 mPa·s. The invention also relates to a method for preparing low-viscosity liquid sulfur and to liquid sulfur compositions comprising at least one compound of formula (1).