Crystallization kinetics and structure of (85TeO(2) + 15TiO(2)) and (85TeO(2) + 10TiO(2) + 5Fe(2)O(3)) glasses are studied using differential scanning calorimetry DSC, IR spectroscopy and XRD. DSC curves in the temperature range from 50 to 525 degrees C with different heating rates from 10 to 40 degrees C/min are used to study the crystallization behavior of the glasses and effects of different heating rates on the glass transition and crystallization temperatures (T-g and T-p). The activation energies of the glass transition and crystallization processes were determined from the shift of T-g and T-p with the heating rates using Kissinger＇s formula. Effects of the polymorphic nature of TeO2 on the crystallization mechanisms are discussed and the phases crystallized during the DSC process were identified by XRD. IR spectra in the frequency range (500-4000 cm(-1)) are measured and possible coordination states of the constituent oxides are discussed for heat-treated and untreated glasses.