A facile, rapid, sensitive and inexpensive spectrophotometric method for the determination of propoxur in insecticidal formulations (samples dissolution in methanol) and fortified water, grains (extraction with CHCl3). Propoxur, also known as undeen or arprocarb contains the active ingredient 2-isopropoxyphenyl-Nmethylcarbamate. Alkaline hydrolysis yields 2-isopropoxyphenol, which couples directly with diazotized 4- aminopyridine, in a weakly alkaline medium, to give a yellow coloured phenol derivative (λ max 469nm). Beer’s law was obeyed over concentration range of 0.5-12μg ml-1.Molar absorptivity and sandell’s sensitivity were found to be 3.268×104 l mol-1 cm-1 and 0.007 μg cm -2 .Method has been satisfactory applied for propoxur in various environmental samples