Transpiration, being the main water transport mechanism in plants, can be significantly impacted by the concentration of salts in the soil. This study aimed to investigate the influence of soil salinity and sun exposure on the transpiration of African mahogany seedlings in a semi-arid region. The research was conducted using drainage lysimeters, in which African mahogany (Khaya senegalensis) seedlings were grown, and different levels of salinity were applied to the irrigation water, ranging from 0.5 dS.m-1 to 5 dS.m-1 in seven different treatments. Each treatment was replicated three times, totaling 21 experimental units (plants), with the aim of optimizing the management of water resources in semi-arid environments. Relevant environmental data, such as photosynthetically active radiation (Qleaf), water potential and electrical conductivity, were collected directly in the field over four months after planting the seedlings in the lysimeters, located in an experimental field in Bahia. Perspiration assessment was performed using a steady-state diffusion porometer model LCpro-SD. The electrical conductivity of the irrigation water was monitored with a portable conductivity meter, being adjusted with the addition of sodium chloride (NaCl) to achieve different salinity levels. Regression analyzes were applied to understand how environmental variables influence the transpiration of mahogany plants. The results indicate that leaf transpiration decreases as the electrical conductivity of the water increases, especially in periods of water restriction. These findings provide valuable insights into the response of African mahogany seedlings to soil salinity and sun exposure, contributing to a better understanding and management of water resources in semi-arid regions.