A half diallel set among six parents of Egyptian cotton was un‌dertaken to evaluate general and specific, combining ability and their in‌teractions with environment in three different locations. The six parents, 15 F1 hybrids and 15 F2 populations were included in three randomized complete blocks design experiments at the three locations. Analysis of variance showed highly significant differences among genotypes for all traits except uniformity ratio. Seed cotton yield, lint yield, number of boils/plant and boll weight were the most affected characters by the environmental variables. The average estimates of heterosis were the highest for these traits. GCA/SCA variance ratio re‌vealed that the non-additive genetic variance was more important in the inheritance of these characters, suggesting the utilizing of heterosis to improve these characters. The additive genetic variance was the most important for lint percentage, lint index and fiber properties. Significant GCA and SCA by locations interactions were observed for several traits indicating that a range of environments is needed to better evaluate hy‌brid combinations. The best general combiners were; Giza 81 for most agronomic characters, Giza 83 x (Giza 72 x DelCero) for boll number and lint percentage, Giza 77 for fiber length and fiber strength traits and Giza 84 for fiber fineness. Crosses exhibiting highest SCA effects were 81 x [Giza 83 x (G.75 x Delcero], Giza 85 x Dendera for yield and num‌ber of bolls and Giza 77 x Giza 84 for fiber length.