Abstract: A process for the preparation of isophorone nitrile utilizing solutions of lithium hydroxide or lithium cyanide, solid LiOH or solid LiOH.cndot.H.sub.2 O as a catalyst. The reaction is carried out under precisely controlled temperature conditions and cyanide feed rate profiles to maintain a reasonably constant concentration of non-reacted cyanide, thereby minimizing the formation of undesirable diisophorone, its nitrile derivative(s) and HCN polymers. A polyacidic acid can be used to acidify the batch, followed by filtration to remove the precipitated lithium salt of the acid, and vacuum distillation to remove liberated HCN and excess isophorone. The resulting isophorone nitrile is obtained in high yield and with low impurity content.