PbO–Al 2 O 3 –SiO 2 :Ho 2 O 3 glasses containing varying concentration of Al 2 O 3 were synthesized. Some pre-structural information of the glass network is obtained using IR spectra. Optical absorption, luminescence spectra and their decay were recorded at ambient temperature. The emission spectra exhibited intense bands corresponding to 5 F 3 → 5 I 8 , 5 F 4 + 5 S 2 → 5 I 8 , 5 F 5 → 5 I 8 and 5 F 4 → 5 I 7 transitions of Ho 3+ ions. The intensity of all these bands showed an enhancement with increasing Al 2 O 3 content. Such increase is caused by decrease of luminescence quenching due to de-clusterization of Ho 3+ ions by Al 3+ ions in the glass network. In addition, self up-conversion due to 5 F 5 → 5 I 8 transition is predicted to populate additionally 5 F 2 and 5 F 4 + 5 S 2 levels and contribute to enrich the green emission. Such up conversion is quantitatively explained using rate occupation kinetics equations and transition probabilities.