The short-term effects of acid rain on the geotechnical properties of residual soil were investigated. Artificial acid rain (AAR) of pH values 2, 4 and 6 was created with an infiltration setup to replicate the interaction between acid rain and soil. The soil specimens were infiltrated with AAR for durations of 30mins and 60mins for each pH level of 2, 4 and 6 and a control sample using deionised water of pH 7.5. Unconfined compression test (UCS) and Atterberg limits test were performed on the treated samples to study the mechanical behaviour and the characteristics of the soil once contaminated with AAR. The results revealed that reducing the pH value of AAR led to a reduction in compressive strength and Young’s modulus and an increment in liquid limit while the plastic limit remained unchanged. The reduction in compressive strength due to acid rain was observed to be almost halved when the bulk unit weight of the soil was increased for the same infiltration period.