The current work was conducted at the Experimental Research Station, Faculty of Agriculture, Aswan University. During the seasons of 2022/2023 and 2023/2024. The crosses and their parents were grown in a Randomized Complete Block Design (RCBD) with three replications. In the first season, half-diallel crosses were made among five genotypes in 2022/2023, and all genotypes were evaluated in the second season 2023/2024. This work aims to evaluate 15 genotypes of Hordeum spp, i.e., five parents and ten F₁-hybrids under normal and water stress conditions for yield and related traits. Moreover, general combining ability (GCA), specific combining ability (SCA), and heterosis based on both mid-parent and better-parent were estimated. The results indicated that the performance of all genotypes under water stress conditions was lower than under normal conditions, except spike length, the earliest parent 5 (P5) headed after 61.33 and 57.50 days of sowing under normal and water stress conditions, respectively. The earliest hybrid was P1× P2, which recorded 74.33 and 73.00 days under normal and water stress conditions, respectively. The ratio of GCA/SCA was lower than one for all studied traits. This indicates that the non-additive (dominance and epistasis) effect is more critical than the additive effect for all traits. As for heterosis, the best cross was P4xP5, and estimated values of significant and positive 34.41 and 19.29 under normal irrigation and 35.83 and 19.78 under water stress conditions compared to mid-parents and better parent, respectively, for grain yield/m².