Tomato is often thermally processed. Chlorpyrifos-ethyl, a broad-spectrum organophosphate pesticide, is widely used on the tomato plants. Therefore, understanding of the fate of the residues during the tomato thermal processing is important for the calculation of dietary exposure. The effects of thermal processing on the reduction of the chlorpyrifos-ethyl residues in tomato homogenates were investigated. Tomato homogenates spiked with chlorpyrifos-ethyl were subjected to thermal processing at the commonly used temperature values (60-90 degrees C) at various time intervals (10-60 min) in the production of tomato products. A QuEChERS technique for sample preparation and a gas chromatograph-electron capture detector for analysing chlorpyrifos-ethyl residues in tomato homogenate were used. The results were further confirmed by using a gas chromatography-mass spectrometry system. Reduction rate of the chlorpyrifos-ethyl residues was as high as 55.8% at 90 degrees C for 60 min. Degradation rates could be considered as first order kinetics model. Apparent activation energies (Ea), temperature coefficients (Q(10)), half time (DT50) and time to reduce to 90% of the initial value (DT90) of chlorpyrifos-ethyl were calculated as kinetic parameters. The results of this study could shed light on the fate of chlorpyrifos-ethyl residues during tomato processing and may also prove invaluable in estimating potential risk from dietary exposure.