Liquid polysulfide polymers with the thiol groups on the end of the chains and of the average molecular weight of 7000-510 g mol(-1) have been obtained by the reaction of BClE and Na2S3, i.e., Na2S2.5 in the presence of hydrazine. The average molecular weight of the obtained polymers depends on the quantity of hydrazine used for the syntheses. With the aim to obtain polymers of the similar average molecular weight it is necessary to use on average 0.5 mol of hydrazine per polymer segment less if Na2S2.5 is used instead of Na2S3. The sulfur content in the obtained polymers is on average less than 2 sulfur atoms per polymer segment and amounts to 1.90 sulfur atoms when Na2S3 is used and is 1.76 sulfur atoms per polymer segment when Na2S2.5 is used for the synthesis.