In the present scenario, Ordinary Portland Cement (OPC) is the most widely used binder in concrete. Production of OPC requires large amount of energy and has a large carbon footprint, emitting approximately 5% of global CO2 emissions annually, which works out to one ton of CO2 emission for every one ton of production of OPC. Geopolymer-based cement concrete (GPC) is a relatively new material with the potential to be an alternative to OPC. GPC has a lower environmental impact, resulting in approximately 85% less CO2 in production, as compared to OPC. Geopolymer can be produced from mineral admixtures, such as fly ash, ground granulated blast furnace slag, metakaolin, and silica fume, with alkaline liquids. Hence, in the present research work, an attempt has been made to explore the possibility of using fly ash-based geopolymer in mortar and to find out its compressive strength by considering the parameters such as effect of ratio of sodium silicate to sodium hydroxide ratio, effect of alkaline liquid to fly ash ratio and effect of age of geopolymer mortar. From the results, it is concluded that with three different ratios of AL/FA, three different ratios of Na2SiO3/NaOH and four different periods of curing, AL/FA = 0.30 and Na2SiO3/NaOH = 1.0 yielded better compressive strength, and hence these proportions are recommended for use in fly ash-based geopolymer in mortar.