The phosphorus doped molybdenum oxide compound (P0.18Mo4.00O12.66). isostructural with molybdite was synthesized in the process of thermally induced phase transformation of 12-molybdophosphoric acid. The synthesized phases (low and high temperature) and the precursor compound (e-phase) have been characterized by thermal (DTA and TGA), X-ray powder diffraction, electron scanning microscopy and spectroscopic (IR) methods. The temperature dependence of electric conductivity sigma(omega-->0) is discussed. It was concluded that the electronic conductivities of bronzes obtained from heteropolyacids are very similar to those of corresponding anhydrous polyacids.