Graphical Abstract: We have investigated the properties as dyes of coordination compounds synthesized by us previously (8-(1',2'-naphthyl)-1-R-3-methyl-6-thiomethyl-4,5,7-triazanona-1,3,5,7-tetraenato-1,1'-diolato(-)-O1, O1', N4, N7-vanadil, where R=CH3 (1) , C6H5 (2)), which can be used for colouring thermoplastic masses. The compounds have a high photostability (7 points), thermostability (>250°) and an intensity of colour that give a low consumption (0.006-0.010g).