Metformin HCl is an oral anti-diabetic medicine which keeps the blood sugar level under control. It’s extensively used in Type 2 (non-Insulin dependent) diabetes. The present study undertaken aims at the formulation development and evaluation of extended release tablets of metformin HCl, which releases the drug in a sustained manner over a period of 12 hours. Two different grades of Hydroxy Propyl Methyl Cellulose (HPMC) namely K15M and K100M were used for the preparation of tablets. The tablets were prepared by wet granulation method and evaluated for thickness, weight variation; hardness, friability, disintegration time, and percentage drug content, invitro drug release and Fourier transform infrared (FT-IR) spectroscopy. During the study it was found that the formulation F11 can be considered as an ideal or optimised formulation for extended release tablet of metformin HCl. The optimised formulation showed sufficiently sustained drug release for more than 12 hours. As the concentration of HPMC increased the drug release pattern declined.