Studied the dissipation behavior of Kresoxim-methyl in acidic, neutral and basic water of pH 4.0, 7.0 and 9.0, an experiment was conducted by spiking in three different pH Waters having pH 4.0, 7.0 and 9.0 to give the uniform concentrations of T0 – Untreated Control, T1 –Kresoxim-methyl 50% WG @ 1 mg/L of water and T2 –Kresoximmethyl 50% WG @ 2 mg/L of water. The spiked samples have been kept under sunlight. The sampling occasions were 0, 1st, 3rd, 5th, 7th, 10th, 15th and 20th day for acidic water (pH 4.0), neutral (pH 7.0) and basic water (pH 9.0) Samples were collected on different occasions (0, 1, 3, 5, 7, 10 and 15). All of the samples had been analyzed until the residues have been below detectable level. The residues of Kresoxim-methyl were quantified using a validated HPLC-UV method. The DT50 (Half Life) of Kresoxim-methyl calculated by regression analysis from the dissipation data.