Arsenic contamination in drinking water has been recorded as a problem of global concern. This study aims to investigate As retention on goethite and gibbsite as a function of pH with similar site densities of >FeOH and >AlOH of natural red earth (NRE), to ensure that these two will make out the same adsorption as >Fe and >Al sites of NRE. 0.385 μmol/l of arsenite and arsenate were spiked separately to solid suspensions, with adjusted pH from 4.0 to 9.0, and equilibrated for 24 h. Final pH were recorded and supernatant was analysed for As after centrifugation and filtration. Data were modelled using a generalized diffuse layer model. Arsenite adsorption was low for gibbsite (50%) than goethite (<95%) and showed a parabolic behaviour, which was not apparent in NRE. Arsenate adsorption was high (>90%) for both solids and showed no pH dependency. Model calculations were fitted well and the model validation was successful with a variation of >AlOH and >FeOH (10-fold) site concentration on NRE.