Abstract3,3′‐Diethyl‐Δ5,5′‐birhodanine (III, R  C2H5) was obtained as a by‐product from the reactions of 3‐ethylrhodanine with 2,4‐dinitrobenzaldehyde and 1‐chloro‐2,4‐dinitrobenzene under suitable conditions. The synthesis of 5‐arylidene substituted rhodanines was achieved from condensations of rhodanines with anils of aromatic aldehydes in glacial acetic acid. III (R  C2H5, CH2· CHCH2and CH2COOC2H5) were prepared by heating the appropriate rhodanines in pyridine containingp‐toluenesulphonyl chloride. Reduction of III with zinc and glacial acetic acid gave the corresponding 5,5′‐birhodanines, which were easily auto‐oxidised in solutions to the related III. Rhodanine and some of its congeners react with 1‐chloro‐2,4‐dinitrobenzene in ethanol containing sodium acetate to give 2,2′,4,4′‐tetranitrodiphenyl sulphide. The methylene group of 3‐aminorhodanine reacted withp‐nitrobenzaldehyde in boiling ethanol, while the amino group was attacked when the reaction was carried out in glacial acetic acid at room temperature. Pyridin