||The aim of the present study was to develop a new theophylline hard gelatin capsule drug delivery formulation. The formulation have been prepared to enhance its dissolution which could provide better oral absorption of theophylline. Therefore, the effects of the component nature and their proportion in the release rate were investigated. Extended release capsules of theophylline were prepared by physical mixing using HPMC and cellulose acetate phthalate (CAP) at various drug-polymer ratios. Hydroxy propyl methyl cellulose (HPMC-E50) ratio was changed the release profile of theophyline. The optimum CAP % was selected as 75 % according to in vitro release studies. Flow properties of the F8 physical mixtures were evaluated by calculation of the Carr’s index, angle of repose and Hausner ratio.The results of the study indicate that new extended release hard gelatin capsules can be promising alternative for the other oral formulations of theophylline.