Three types of cyanorhodanines have been synthesized for evaluation as fungicides for the protection of cellulose. The first group comprised five cyanobenzylidenerhodanines prepared by the condensation of 4‐cyanobenzaldehyde with rhodanine and its 3‐allyl, ‐carboxymethyl, ‐ethyl and ‐phenyl congeners. The corresponding carboxy analogs were similarly synthesized from terephthaldehydic acid. The second group consisted of cyanobenzylidenerhodanines containing a β‐cyanovinyl aromatic side‐chain introduced by the condensation of ethyl cyanoacetate with formylbenzylidenerhodanines. The latter are versatile intermediates for the synthesis of substituted rhodanines and a convenient procedure for their preparation is now reported. The third type of cyanorhodanines contained a β,β‐dicyanovinyl aromatic side‐chain correspondingly prepared from the formylbenzylidenerhodanines by condensation with malononitrile.