Ordinary Portland Concrete (OPC) is the most widely used construction material all over the world. Using OPC contributes to the global warming through emission of billions tons of Co2 to the atmosphere. Due to this, much efforts are played to develop innovative and environmentally friendly construction materials such as geopolymers concrete. This paper investigated the setting process of geopolymers pastes as affected by different parameters. Alkaline solution to fly ash ratio, concentration of sodium hydroxide in terms of molarity as well as the composition of the alkaline solution (Na2SiO3/ NaOH) ratios were investigated. Both the initial and final setting time values were evaluated. The results indicated that increasing NaOH molarity and /or its ratios in the solution, the setting developed faster due to the formation of the initial calcium silicate hydrates. Moreover, increasing Na2SiO3 in the solution, delayed the setting process due to the formation of sodium calcium carbonate which retarded the reaction process. Due to the complex and overlapping of the studied parameters affecting setting times of geopolymers pastes, contour plots are established for both initial and final setting times. Moreover, the consistency as well as the compressive strength of the conducted mixtures are evaluated for geopolymer mortar.