¹Faculty of Pharmacy, Jember University, Jember, Indonesia DOI : 10.29228/jrp.872 This study aims to produce quercetin-maleic acid cocrystals with an increase in solubility properties. The preparation of quercetin-maleic acid cocrystal (CQAM) was carried out by solvent evaporation method using ethanol as a solvent. The quercetin-maleic acid cocrystal preparation was formed with two different stoichiometric ratios, namely quercetin-maleic acid (1:1 and 1:3). Solubility tests on quercetin-maleic acid cocrystals were carried out in 50 mL citrate buffer pH 5 at 37±0.5°C. The characterization tests used were DSC, PXRD, FTIR, and SEM, while for the evaluation, solubility tests were carried out. The results of DSC, PXRD, FTIR and SEM showed the formation of a new solid with the type of crystalline solid, so it was concluded as a cocrystalline solid. The results of the solubility test showed that the solubility value of quercetin-maleic acid cocrystal (1:1 and 1:3) was greater than that of pure quercetin. Solubility result of pure quercetin, CQAM 1:1 and CQAM 1:3 were 0.545 ± 0.0351 mg/L; 2.237 ± 0.0258 mg/L; and 6.352 ± 0.0258 mg/L, respectively. Quercetin–maleic acid cocrystals (1:1) and (1:3) experienced an increase in solubility of 4.11 and 11.65 times, respectively, from pure quercetin. Keywords : Cocrystal; Quercetin; Maleic Acid; Solvent Evaporation; Solubility