Sulfuric acid attack is an important aspect in the long-term mechanical and durability performance of geopolymer concrete. Keeping this in view, in this study the effect of sulfuric acid attack on compressive strength was investigated, as well as the microstructural changes of geopolymer mortar mixtures. Geopolymer mortar mixes were prepared by activating metakaolin with a mixture of dealuminated kaolin (DK) and sodium hydroxide (NaOH) suspension as an alkaline activator and cured at ambient temperature. The effect of diluted sulfuric acid solution (pH=3) was investigated after 28 days of curing at ambient temperature. A comprehensive experimental program was carried out, including the evaluation of compressive strength, sorptivity, absorption, and volume of permeable voids prior to acid exposure. Over a ten-week exposure period, weight change and strength degradation were assessed. Microstructural analyses using scanning electron microscopy (SEM) and energy-dispersive X-ray spectroscopy (EDS) were conducted before and after exposure to confirm the findings. The results of the study revealed that the formed geopolymer mortars resist the sulfuric acid (5%). It was found that about a 21.7% reduction in the compressive strength was recorded.