The preparation and properties of pure tin(II) thiocyanate and of several complex thiocyanates are described. Their infrared spectra are discussed and evidence is adduced for mainly N-bonding of the thiocyanate, with extensive bridging in Sn(NCS)₂. Tin(II) thiocyanate is found to form ether adducts of poor stability and to be an effective catalyst for polyurethane foam formation. X-Ray powder data are given for Sn(NCS)₂, KSn(SO)₄NCS, CsSn(NCS)₃, Me₄NSn(NCS)₃, and Et₄NSn(NCS)₃.