ATP-sulphurplase was found in the soluble fraction of cell extracts of rice shoots. The enzyme was purified 44-fold by ammonium sulphate fractionation, DEAE-cellulose and sephadex G-200 chrmatography. The optimum temperature of the enzyme is around 40°C while its pH optimum is between 7.5-8.5. Mg⁺⁺ is required for its activity but group VI anions (molybdate, sulphate, selenate, tungstate), EDTA, Hg²⁺, azide, cyanide, sulphide and fluoride are inhibitory. The Km values for APS and pyrophosphate are 4.5 µM and 9.0 µM respectively.