<p>In this study, the solubility of sulfasalazine in supercritical carbon dioxide, using ethanol as a cosolvent, was evaluated at temperatures of 308, 318, 328, and 338&#xa0;K, and at pressures reaching up to 30&#xa0;MPa. A comprehensive examination was conducted to ascertain the impact of temperature, pressure, and cosolvent concentration on solubility and density. To this end, SRK as an equation of state and a range of semi-empirical correlations were employed to correlate the solubility. The Soltani-Mazloumi and Madras et al. models were identified as the most suitable model for the experimental data. The mole fraction of sulfasalazine ranged from 0.273 × 10⁻⁴ to 1.654 × 10⁻⁴ in the binary system, and from 1.535 × 10⁻⁴ to 5.211 × 10⁻⁴ and 3.263 × 10⁻⁴ to 11.451 × 10⁻⁴ at concentrations of 1 and 3&#xa0;mol%, respectively. The findings indicated that the incorporation of a cosolvent, notably ethanol, led to a substantial enhancement in solubility. The sulfasalazine-ethanol-CO₂ system demonstrated the highest solubility at 12&#xa0;MPa and 338 K, exhibiting approximately 11.95 times greater solubility compared to that observed in pure supercritical CO₂.</p>