Described is a process for the integrated production of hexamethylenediamine. The process includes integrating an HCN production process, a dinitrile compound production process, and a diamine production process. The HCN production process provides HCN for hydrocyanating butadiene to form a dinitrile compound and a hydrogen stream for hydrogenating the dinitrile compound to form a diamine. The HCN production process includes forming a crude hydrogen cyanide product and separating the crude hydrogen cyanide product to form an off-gas stream and a hydrogen cyanide product stream. The off-gas stream is further separated to recover hydrogen. The hydrogen cyanide product stream is further processed to recover hydrogen cyanide.