This study investigates whether adding 5% (w/w) biochar to saline soils can mitigate the negative effects of salt stress on lettuce (Lactuca sativa L.) plants. Six NaCl concentrations (0, 50, 100, 200, 300, and 400 mM) were tested, with and without biochar. The results showed that biochar significantly improved several physiological and biochemical parameters of lettuce plants, including total chlorophyll content, fresh weight, total antioxidant power, and total soluble proteins. However, biochar did not effectively reduce Na accumulation in lettuce leaves. Free amino acid content was not significantly affected by biochar, but several parameters, such as total antioxidant power, fresh weight, and chlorophyll content, were enhanced. The study also found that biochar increased the content of K and Zn in lettuce leaves. While biochar showed some effectiveness in mitigating the negative effects of salt stress, it did not fully counteract Na accumulation. The findings suggest that biochar can be a viable solution for mitigating the damage caused by high salt concentrations on plant growth, particularly at lower NaCl concentrations. However, at higher concentrations, the effectiveness of biochar is limited. The study highlights the potential of biochar as an eco-friendly solution for soil salinity management in agriculture.This study investigates whether adding 5% (w/w) biochar to saline soils can mitigate the negative effects of salt stress on lettuce (Lactuca sativa L.) plants. Six NaCl concentrations (0, 50, 100, 200, 300, and 400 mM) were tested, with and without biochar. The results showed that biochar significantly improved several physiological and biochemical parameters of lettuce plants, including total chlorophyll content, fresh weight, total antioxidant power, and total soluble proteins. However, biochar did not effectively reduce Na accumulation in lettuce leaves. Free amino acid content was not significantly affected by biochar, but several parameters, such as total antioxidant power, fresh weight, and chlorophyll content, were enhanced. The study also found that biochar increased the content of K and Zn in lettuce leaves. While biochar showed some effectiveness in mitigating the negative effects of salt stress, it did not fully counteract Na accumulation. The findings suggest that biochar can be a viable solution for mitigating the damage caused by high salt concentrations on plant growth, particularly at lower NaCl concentrations. However, at higher concentrations, the effectiveness of biochar is limited. The study highlights the potential of biochar as an eco-friendly solution for soil salinity management in agriculture.