This paper reports on the spectral analysis of Eu3+ or Tb3+ ions (0.5 mol%) doped heavy metal oxide (HMO) based zinc lead berate glasses from the measurement of their absorption, emission spectra and also different physical properties. From the XRD, DSC profiles, the glass nature and glass thermal properties have been studied. The measured emission spectrum of Eu3+ glass has revealed five transitions (D-5(0) -> F-7(0), F-7(1), F-7(1), F-7(3) and F-7(4)) at 578, 591, 613, 654 and 702 nm, respectively, with lambda(exci) = 392 nm (F-7(0) -> L-5(6)) ln the case of Tb3+:ZLB glass, four emission transitions such as (D-5(4) -> F-7(6), F-7(5), F-7(4) and F-7(3)) that are located at 489, 542, 585 and 622 nm, respectively, have been measured with lambda(exci) = 374 mn. For all these emission bands decay curves have been plotted to evaluate their lifetimes and the emission processes that arise in the glasses have been explained in terms of energy level schemes. (c) 2006 Elsevier B.V. All rights reserved.