Anharmonic vibrational frequencies are calculated for the H-n(+) clusters (n=5,7,9) employing the correlation-corrected vibrational self-consistent field method. The present results confirm previous experimental assignments and also allow us to assign the 6690 cm(-1) band of the H-5(+) cluster. The results explain the lack of features in the photodissociation spectra of the H-7(+) and H-9(+) clusters, in the region of 3000-3600 cm(-1). The calculation also provides enough reliable data for the identification of these clusters in hydrogen atmospheres. The nature of the excitations near 4000 cm(-1) in the vibrational spectra of the H-7(+) and H-9(+) clusters and their implication in the mechanism of photodissociation of these cluster are also discussed. (C) 2003 American Institute of Physics.