In the present paper a detailed analysis of high-resolution luminescence spectra of Eu(III)H2O species in frozen aqueous solution (T = 5 K) is presented. From the total luminescence spectra (TLS, excitation vs emission) and the luminescence decay matrixes (time vs emission), fundamental species-selective spectroscopic parameters are determined: excitation wavelength lambda(exc), decay time tau, crystal field energy splitting Delta E (crystal field strength parameter N-v(B-2q)), crystal field parameters B-20 and B-22, asymmetry ratio r, and point symmetry group. The spectroscopic findings clearly show the presence of two distinct Eu(III) aquo species. Samples prepared with different counterions (Cl-, CIO4-) and at different pH values (2 and 5) yielded comparable results. Furthermore, in D2O solutions the same two species were found, with similar spectral properties but much longer decay times. On the basis of the spectroscopic analysis, the two species were attributed to 8- and 9-fold coordinated Eu(III) aquo ions.