Attempts were made to optimize variables affecting the yield of linseed oil biodiesel in a base catalyzed transesterification reaction. The variables studied were reaction temperature (40-70oC), catalyst (NaOH) concentration (0.1-1.5%) and reaction time (30-180 min). The conversion of linseed oil into methyl esters was confirmed through analytical methods like 1H NMR, gas chromatography (GC) and refractometer. The maximum biodiesel yield (97±1.045% w/w) was obtained at 0.5% catalyst concentration, 65oC temperature, 180 min reaction time and 6:1 molar ratio of methanol to oil. 1H NMR confirmed the practically obtained % conversion of triglycerides into methyl esters which was further evidenced by refractometer analyses. The refractive index of biodiesel samples was lower than pure linseed oil. GC analysis confirmed the presence of linolenic acid (C18:3) as the dominant fatty acid (68 wt. %) followed by oleic acid (C18:1), linoleic acid (C18:2) and stearic acid (C18:0) respectively. The physical properties of linseed oil biodiesel like specific gravity (0.90 g/cm3) and flash point (177oC) were higher than American Society for Testing and Materials standards (ASTM 6751) for biodiesel. However, kinematic viscosity (3.752 mm2/s) was in the range of ASTM standards.