Nine new white maize inbred lines were topcrossed with four line testers, i.e., Sd.1185, Sd.1194, Sd.1264 and Sd.1313 during 2020 summer season. All inbred lines were developed at Sids Agricultural Research Station. The 36 testcrosses and the two check hybrids SC10 and SC2031 were evaluated at Sakha, Gemmeiza and Sids Agric. Res. Stns. during 2021 summer season. General (GCA) and specific (SCA) combining ability effects were estimated for days to 50% silking, plant height, ear height, ear position (%) and grain yield (ardab/feddan). Combined analysis across the three locations showed significant differences between the three locations for all studied traits. Mean squares due to crosses, lines and testers were significant for all studied traits. Mean squares due to lines × testers were significant for days to 50% silking, plant height, ear height and grain yield. Mean squares due to lines × locations were significant for all studied traits. Mean squares due to testers × locations were significant for all studied traits, except for grain yield. Mean squares due to lines × testers × locations interaction were highly significant for days to 50% silking. The magnitude of δ2 GCA (average) was larger than that of δ2 SCA for all studied traits except, for plant height and grain yield. The inbred lines L.2 and L.4 possessed the highest GCA effects for grain yield and may be considered promising lines for improving grain yield. Also the crosses L.4×Sd.1185, L.13×Sd.1264 and L.20×Sd.1194 may be released for commercial cultivation after further testing and evaluation. The inbred lines, based on grain yield and heterotic group using specific and general combining ability (HSGCA) method, were classified into four heterotic groupings as follows: group-1 (Sd.1185) included L.14 and L.22 while, group-2 (Sd.1194) included L.22. Group-3 (Sd.1264) included L.4, L.9 and L.20 while, group-4 (tester Sd-1313) included L.12 and L13. These groups could be used in breeding programs for selecting the best parents in developing new crosses.