The conditions for the preparation of solutions, in some common solvents, of single species of molybdenum(V) tetraphenylporphyrin chloride complex, OMoTPP(Cl) (I), molybdenum(V) tetraphenylporphyrin hydroxide complex, OMoTPP(OH) (II), their respective hydrochlorides, OMoTPP(Cl)·HCl (III), and OMoTPP(OH) (IV), ethoxide complex, OMoTPP(OEt) (V) and the μ-oxo-dimer, OMoTPP) 2O(VI) have been estblished. In contrast to the previous results, reproducible visible spectra, characteristics of metalloporphurins were observed. Two sets of esr spectra, corresponding respectively to the interaction of d′-electron of 26Mo isotope wiht the nuclear moment of 4 nitrogen atoms of the porphyrin ring system and the interaction of d′-electron of the 95Mo and 96Mo isotopes with the 5/2 nuclear moment of the same isotopes of molybdenum, were recorded for these solutions. The visible spectral results and the esr absorptions were found to be mutually consistent.