The hydrolysis of substituted 3-(3-cyanothiophen-2-yl)imino-3 H -furan-2-ones was studied. It was found that the reaction proceeds with the opening of the furan ring and the formation of the corresponding 4-oxo-2-(3-cyanothiophen-2-yl)aminobut-2-enoic acids. The antibacterial activity of the obtained compounds against Staph ylococcus aureus , Escherichia coli and Candida albicans was studied.