Two field experiments were conducted during winter seasons of 2018/2019 and 2019/2020 in the Experimental Farm, Faculty of Agriculture and Nature Resources, Aswan University, Aswan, Egypt. The main objective behind this study is to investigate the effectiveness of foliar application of potassium silicate (control , 1000, 2000, 3000 mg.l^-1) which were sprayed four times with two weeks intervals, on the performance of three tomato hybrids (Salymia (65010), 023 and El- Quds (E-448)) under arid conditions to overcome or alleviate the heat stress (temperature difference between day and night) during tomato growing seson at Aswan governorate, Egypt. Generally, the foliar application of potassium silicate at 3000 mg.l^-1resulted in vigor tomato plant as expressed by vegetative growth parameters i.e., number of leaves per plant, number of branches per plant and plant foliage fresh and dry weights as compared to other foliar treatments. Moreover, it gave the highest values of fruit yield and chemical composition of leaves and fruits. In addition, El-Quds (E-448) tomato hybrid gave the highest vegetative growth, yield parameters and chemical composition of leaves and fruits. The interaction effects among the studied treatments were significant in all studied parameters. Generally, results indicated, that El-Quds (E-448) tomato hybrid sprayed with potassium silicate at 3000 mg.l^-1 might be considered as an optimal treatment to produce high vegetative growth, yield and fruit quality of winter tomato under the environmental conditions of the experimental condition at Aswan governorate and other similar regions.