In this investigation, nine inbred lines of yellow maize from various sources were evaluated to determine the type of gene action and combining ability. At the Sids Agric. Res. Sta. all possible combinations of these lines were developed in a half diallel during the 2022 growing season (Griffing's 1956 method 4 model 1), giving 36 crosses. In 2023 season 36 crosses along two commercial hybrids SC.168 and SC.3444 were evaluated in replicated trials conducted at three locations; Sakha, Gemmeiza and Sids Agric. Res. Sta. Recorded were the days to mid-silking, plant height (PHT) cm, ear height (EHT) cm, ear position (%) and grain yield (ardab/fed). The findings revealed significant differences among the three locations for all the studied traits, suggesting that the environmental conditions varied among all three locations. Except for plant height, the mean squares of genotypes, crosses, and their interactions with locations were highly significant for traits under study. The findings revealed that for all traits under study, the variances in general and specific combining abilities were highly significant, suggesting that both additive and non-additive gene action played an essential role in the inheritance of these traits. The parental lines Sd.3299, Sd.3234, Gz.658 and Mall.5035 had favorable GCA effects on grain yield. Eight crosses (Sd.3187 × Sd.3234), (Sd.3187 × Gz.658), (Sd.3195 × Sd.3299), (Sd.3299 × Sd.3242), (Sd.3300 × Sd.3234), (Sd.3300 × Mall.5035), (Sd.3220 × Sd.3242) and (Sd.3242 × Gz.658) had positive and significant SCA influence on grain yield.