A simple, precise, accurate, cost effective and alternative isocratic high performance liquid chromatography method was developed for the estimation of metformin hydrochloride in bulk and in granule formulation. Chromatographic separation was achieved with Eclipse XDB C18 column (150.00 mm × 4.60 mm) utilizing a mobile phase of sodium chloride, sodium pentane sulfonate along with triethylamine (50.00% W/W). Orthophosphoric acid was added to adjust the mobile phase pH to 3.8. It was filtered through 0.45 μ membrane filter and detection was carried out at 233 nm using PDA detector. Validation was performed as per ICH guidelines to demonstrate system suitability, specificity, linearity, accuracy, precision, limit of detection, limit of quantitation, robustness, ruggedness. The linear response (r2 = 0.999) was observed in the range of 25-75.00 μg mL-1 with good recoveries (99.79% to 101.75%). Validation acceptance criteria were met in all cases. Thus, the method can be used in pharmaceuticals for routine quality control assay of metformin hydrochloride.