Background and Objectives: Salinity is one of the abiotic stress factors that causes great damage to the production of agricultural products around the world. Various strategies have been adopted to reduce the negative effect of salinity on plants and to improve the growth and development of plants under salinity stress conditions. In the present study, the effect of silicon foliar application on decreasing the effects of salinity stress and its related physiological mechanisms in hot pepper plants has been investigated. Materials and Methods: The research was conducted as a factorial experiment based on completely randomized design with three replications in the greenhouse of Ilam University. The treatments tested in this research included three levels of salinity stress (control, 75 and 150 mM NaCl) and four levels of silicon (control, 0.5, 1 and 2 mM). In the stage of four expanded leaves, silicon treatment was applied as a foliar spray in the mentioned concentrations until the surface of the leaves was completely wet, and it was repeated two more times after one month. Salinity treatment was done by preparing NaCl solution and i the plants with fertilizer solution every three days. The treatments were continued until fruiting and complete fruit harvesting. Results: In the final results obtained from this research, it was found that salinity caused a significant decrease in growth and performance parameters (root and shoot dry weight, plant height, number of fruits per plant and crop yield) as well as a decrease in relative water content and chlorophyll and caused increase in the content of proline, malondialdehyde and ion leakage in pepper plants. The results showed that the application of silicon reduced the effects of salinity stress on pepper plants. The highest total yield was obtained in 1 and 2 mM silicon application under non-saline irrigation. At all salinity levels, the application of silicon increased the growth and yield of pepper plants. These results were related to the increase in relative water content and chlorophyll, and decreases in proline, malondialdehyde accumulaion and electrolyte leakage. Conclusion: In general, the results of this research indicated that the application of silicon, especially in concentrations of 1 and 2 mM, improved the growth and performance of hot pepper plants under stress and non-stress conditions. The exogenous application of silicon alleviated the negative effects of salinity on the plant by increasing the amount of chlorophyll and relative water content and decrease proline and malondialdehyde. Although the application of silicon in non-saline conditions had positive effects on plant growth and performance, it was more effective in saline conditions. Therefore, silicon foliar spraying is recommended to decrease the effects of salinity on the growth and performance of hot pepper plants. [ABSTRACT FROM AUTHOR]