In this study, 51 V, 45 Sc and 93 Nb MAS NMR combined with satellite transition spectroscopy analysis were used to characterize the complex solid mixtures: VNb 9.1-x/ Ta 9x O 25 , ScNb .1-x/ Ta x O 4 and ScNb 2.1-x/ Ta 2x VO 9 (x = 0, 0.3, 0.5, 0.7, 1.0). This led us to describe the structures of Sc and V sites. The conclusions were based on accurate values for 51 V quadrupole coupling and chemical shift tensors obtained with 51 V MAS NMR/SATRAS for VNb 9 O 25 , VTa 9 O 25 and ScVO 4 . The 45 Sc NMR parameters have been obtained for Sc 2 O 3 , ScVO 4 , ScNbO 4 and ScTaO 4 . On the basis of 45 Sc NMR and data available from literature, the ranges of the 45 Sc chemical shift have been established for ScO 6 and ScO 8 . The gradual change of the 45 Sc and 51 V NMR parameters with x confirms the formation of solid solutions in the process of synthesis of VNb 9.1-x/ Ta 9x O 25 and ScNb .1-x/ Ta x O 4 , in contrast to ScNb 2.1-x/ Ta 2x VO 9 . The cation sublattice of ScNb .1-x/ Ta x O 4 is found to be in octahedral coordination. The V sites in VNb 9.1-x/ Ta 9x O 25 are present in the form of slightly distorted tetrahedra. The 93 Nb NMR parameters have been obtained for VNb 9 O 25 .