In this study, gelatin microspheres containing diltiazem hydrochloride (DTZ HCl) were prepared by the polymerization technique using glutaraldehyde as the cross-linking agent. The prepared microspheres were examined for its practical yield, drug content, and release kinetic. The study also includes the effect of processing variables on the result of evaluation. The shape and surface topology of prepared microspheres of various formulations were spherical as investigated by SEM studies. Pure drug and the drug polymer mixture showed similar peak in FTIR study which indicated no interaction between drug and polymer. From dissolution study of formulations, it was concluded that the formulation containing high amount of hydrophobic polymer gave high sustaining effect i.e. 8 hrs. So, the present work successfully achieved the objective of designing of controlled release microspheres of DTZ HCl