The Knoevenagel condensations of various carbonyl compounds with active methylene compounds were reported in water medium without adding any catalyst. The condensation of aromatic aldehydes with active methylene compounds like malononitrile, cyanoacetamide and ethyl cyanoacetate has been found to proceed very efficiently at room temperature giving excellent yields, but the condensation of heteroaromatic, α,β-unsaturated and aliphatic aldehydes with active methylene compounds proceeded smoothly in 50～65 ℃ with good yields and the reactions of aromatic, aliphatic ketones as well as p-phthalaldehyde with malononitrile also proceeded in 75～85 ℃ with moderate yields. The work-up procedure is simple, efficient and environment-friendly.

Key words: carbonyl compound, condensation, active methylene compound, medium