Geopolymers are the inorganic polymer materials possessing properties superior than the properties of conventional materials. Geopolymers are also environment friendly materials. This paper determines the effects of parameters such as silica to alumina (Si/Al) ratio, sodium to alumina (Na/Al) ratio, water to solid (W/S) ratio, and temperature on the setting of fly ash geopolymers. The experiments were designed using Taguchi model. The setting time was determined by Vicat Needle apparatus. The Si/Al - 2.2, Na/Al - 1.4, W/S - 0.30, and temperature of 40 °C increased the setting time and workability of the geopolymers. The Si/Al ratio of 1.8, Na/Al ratio of 1.0, W/S ratio of 0.20, and temperature of 80°C caused fast setting of geopolymers. The setting time of geopolymers can be optimized using Taguchi method for particular applications. © 2016 The Authors.