Compounds with the olivine-type structures are considered as perspective materials for lithium-ion power sources for both industrial and transport applications. Lithium iron phosphate is most highly developed from this family, but LiMnPO4 is supposed as much promising, due to its higher EMF vs. lithium. One of the main lacks of this class of materials is the low electronic conductivity. The traditional ways of conductivity increase by partial replacement of Mn with other transition metal for LiMnPO4 do not result to essential success. Our approach consisting in the influence onto anion sublattice results to better effect. Such solid solutions should be suitable for oxygen nonstoichiometry creation in virtue of ability of vanadium ion for oxidation degree downturn. Using magnetic methods, we succeeded to show that the required solid solutions are really formed. The optimal synthesis conditions of LiMnP1-xVxO4-δ solid solutions were determined. It was shown, that the doping of LiMnPO4 by vanadium jointly with oxygen nonstoichiometry brings to substantial enhance of electronic conductivity in this material. Observed peculiarities of the magnetic properties indicate the restructuring in the local environment in anion sublattice.