<p class="042abstractstekst">Little has been done to evaluate the molecular role of ZnO nanoparticles (ZNPs) in regulating biochemical processes and plant yield in response to salt-induced stress. In this study, the molecular response of salt-stressed soybean (‘Giza111’) was assessed under different concentrations of ZNPs (25, 50, 100, and 200 mg l^-1) by measuring some osmolytes, yield parameters, and Na⁺ and K⁺ content. The impact of salinity on the mRNA expression levels of three key salt-tolerance related genes <em>(GmCHX1,</em> <em>GmPAP3</em><em>, </em>and<em> GmSALT3)</em> using qRT-PCR was also determined. The high level of salinity (250 mM NaCl) led to a significant increase in Na⁺content, total soluble proteins, and total soluble carbohydrates and significantly upregulated gene expression of <em>GmCHX1,</em> <em>GmPAP3, </em>and<em> GmSALT3</em>, while reducing K⁺ content, K⁺/Na⁺ ratio and all yield parameters compared to control plants. Soaking soybean seeds in various ZNP concentrations, on the other hand, increased K⁺ content and K⁺/Na⁺ ratio while decreasing Na⁺ content, total soluble proteins, and total soluble carbohydrates in stressed plants, particularly at 50 mg l^-1 ZNPs. Furthermore, <em>GmCHX1,</em> <em>GmPAP3, </em>and<em> GmSALT3 </em>expressions were all downregulated at 50 mg l^-1 ZNPs, which ultimately improved soybean yield parameters. Accordingly, these results recommend the application of 50 mg l^-1 ZNPs for improving the productivity of soybean cultivated in saline soils.</p>