•Catchment water balance predicted with insignificant change under RCP4.5.•Annual water yield and runoff is predicted to increase by 5 % and 6 % respectively.•Runoff in DJF under RCP4.5 is predicted to increase by 11 %.•Catchment water balance predicted to increase under RCP8.5.•Annual rainfall, water yield and runoff under RCP8.5 are predicted to increase between 19 % – 65 %. The Kabompo River Basin (KRB) in Zambia is one of the 13 basins found in the Zambezi River Basin in Southern African region. Global Climate Model (GCMs) projections have spatial resolution of up to several hundred kilometres, which may not be adequate for capturing local details mostly needed for impact assessment at local and regional scale. Downscaling techniques developed to improve the detail include; regional climate modelling and statistical techniques linking climate information at GCM resolution with that at local scale. This paper deals with evaluation and assessment of the impact of climate change on water balance for the KRB. In order to evaluate climate change impact, six bias–corrected and downscaled GCM outputs were acquired and used as inputs for hydrological modelling with the SWAT model to determine the impact under two future climate scenarios. The results indicate that the future catchment water balance for KRB under RCP4.5 will have insignificant variation from the current catchment water balance as annual statistics show that rainfall will reduce by 1 % while water yield and runoff will increase by 5 % and 6 % respectively. Meanwhile under RCP8.5, annual statistics show that rainfall will increase by 19 % while water yield and runoff will increase by 40 % and 65 % respectively and resulting in a significant increase in catchment water balance.