Abstract: Background and Objective: The objective of this study was to formulate an effervescent floating drug delivery system of metformin using Grewia mollis gum in order to achieve extended release and improve its absorption at the site of action. Materials and Method: Effervescent floating matrix granules of metformin were formulated by wet granulation method using the extracted natural gum at different concentrations (2, 4, 6 and 8% w/w). Sodium bicarbonate (30%) and tartaric acid (5%) were added as the gas generating agents. All granules were analyzed for micromeritic properties. Granules were compressed at an optimized compression pressure of 35 arbitrary unit on the tableting machine load scale. Tablets were evaluated for hardness and in vitro buoyancy test. Drug-excipient compatibility study was done using Fourier Transform Infra-red spectroscopy (FTIR). Results: All the formulated Gastroretentive Floating Matrix (GRFM) granules were free flowing with angle of repose and Carr’s index <31° and <14%, respectively. The floating lag time for GRFM tablets formulated with Grewia mollis was <610 sec. All GRFM granules were compressible with tablet hardness between 2.0-7.3 KPa. There was a significant difference in tablet hardness with increase in binder concentration (p<0.05). Generally, GRFM tablet percentage friability decreased with increase in binder concentration (<0.98%). The FTIR studies shows that the excipients and the Active Pharmaceutical Ingredient (API) i.e., metformin were compatible. Conclusion: Grewia mollis gum has been exploited in the formulation of gastro-floating matrix tablets of metformin which may find useful application for drugs that have narrow absorption window in the upper part of the gastrointestinal tract (GIT).