Department of Chemistry, Ravishankar University, Raipur-491 010 Manuscript received 12 August 1986, revised 18 November 1986, accepted 3 January 1987 A new, simple, rapid and sensitive photometric method is developed is the deter­mination of organophosphorus pesticides in plant materials. The method involves the formation of 12-molybdophosphoric acid from orthophosphate and excess of molybdate in acid solution followed by the reduction with succinyldihydrazide to give molybdenum blue. The dye extracted in n-butanol shows absorption at 780 am. The proposed method is free from the interference of Mo, As and Cu. The molar absorptivity and Sandell's sensitivity are found to he 3.75±0.05 x 10-1 dm-1 mol-1 cm-1 and 000 8 µg, respectively.