The concept of the sintering technique in the pharmaceutical sciences is relatively new.The objective of the present study was to prepare and evaluate thermally sintered gastro retentive floating matrix tablets of Atazanavir sulphate. The formulations were prepared by direct compression method using EC N100 and HPMC K100 as polymer. The prepared tablets were exposed at two different temperatures like 500C and 600C for two different periods like 1.5 hr and 3 hr in a hot air oven. Effects of sintering conditions were studied on in vitro dissolution studies, hardness, friability, floating lag time and total floating time. The sintering temperature and the sintering time markedly affected the drug release properties. The release rate of the drug was inversely related to the sintering temperature and the sintering time. The hardness was increased with increase in sintering temperature and duration of sintering; but friability of tablets was found to be decreased with increasing sintering time. Floating lag time was inversely proportional to the sintering temperature and sintering time, whereas total floating time was directly proportional to the sintering temperature and sintering time. The formulation F2 sintered at 600 for 3 h was selected as an optimized formulation based on the drug retarding properties and the optimized formulation followed Fickian diffusion mechanism with Korsmeyer-Peppas release kinetics. FTIR and DSC studies were used to characterize the optimized formulation and those studies showed no evidence on interaction between the drug and polymer used.