In this paper, the effect of alkali activator to binder (AAB) ratio and molarity of alkaline activator on the rice husk ash based geopolymer were investigated. Compressive strength has been determined on 70.6 × 70.6 × 70.6 mm specimens by varying AAB ratio from 0.5 to 0.7 and molarity of alkali activator solution from 12 M to 16 M. The microstructure was also examined using scanning electron microscope (SEM). Experimental results revealed that the maximum compressive strength is obtained up to 39.95 N/mm 2 after 28 days. It has been observed that compressive strength is directly proportional to both AAB ratio and molarity of alkali activator solution. With increasing the molarity, microstructure become quite dense, this may be attributed to high degree of geopolymerisation .