The triple differential cross section of Ca (4s2) in coplanar symmetric geometry at low impact energies is calculated using a spin averaged static exchange potential and a modified semi-classical exchange potential in Distorted Wave Born Approximation. The calculations have been carried out at incident energies of 10.11, 12.61, 19.61, 24.61, 34.61, 44.61, 54.61 and 64.61 eV for Ca, at which experimental data were available for comparison. The effect of post collision interaction has also been studied using Gamow factor introduced by Whelan et al. (1994). The present calculations have been compared with the recent (e, 2e) experimental studies of Murray (2005) and the earlier theoretical work of Chauhan et al. (2005). The present results are found to be in better agreement with experimental data as compared to the earlier study. © 2007 IOP Publishing Ltd.