In this study, geopolymer samples were prepared by mixing metakaolin (MA) with activator solution made of potassium alkali silicate solution, potassium hydroxide flakes, and additional water. The aim of the experiment is to evaluate the mechanical strength of hardened samples based on four test variables including the SiO2/K2O molar ratios, K2O concentration, H2O/MA water coefficient, and curing temperature. The results reveal that K2O concentration and H2O/MA water coefficient impact strongly on the compressive strength, whereas varying of SiO2/K2O molar ratios in the range from 1.0 – 1.4 does not significantly change the compressive strength of geopolymer samples. On the other hand, high-temperature curing leads to higher mechanical strength of the samples in the early-age compared to curing at room temperature, due to the faster establishment of hard structure in the early-age of geo-polymerization process. However, curing at a temperature range of 80°C – 100°C contributes the non-linear strength development of the samples over the time.