Trichlorfon is a colourless crystalline powder that is stable at room temperature. It is slowly hydrolysed in acid media; the half-life is 526 days at pH 1-5 and 20°C. In alkaline media, at pH 8 and 37.5 °C, it hydrolyses initially to the more toxic compound dichiorvos, but is essentially 100% hydrolysed in 24 h to less toxic products, such as dirnethyl hydrogen phosphate, dichloroacetaldehyde, and givoxal. Trichlorfon also decoin-poses under ultraviolet irradiation.