Two stable diamine complexes [Co(1,1-dmen)2(NCS)2]SCN · (H2O)1.5 (1) and [Co(pn)2(NCS)2]SCN · (H2O)1.5 (2) have been synthesised and characterised by elemental analysis, i.r. and electronic spectra and t.g.a. The structure of (1) has been confirmed by single-crystal X-ray diffraction and reveals that the cobalt complex has octahedral geometry and consists of two crystallographically independent cations, both situated on centres of inversion. In the crystal structure of (1), free H2O molecules and SCN- ions form an extensive hydrogen bonding network with the cation. It is an ordered pseudo-polymorph of a previous structure determination. Both (1) and (2) are diamagnetic.