This study investigated the photocatalytic degradation of CR, MB, and RhB dyes using Co3O4 nanostructures and ZnO-Co3O4 nanocomposites synthesized via solution combustion. Co3O4 nanostructures had an average size of 14.56 nm and a band gap of 1.66 eV, while ZnO-Co3O4 nanocomposites had an average size of 11.12 nm and a band gap of 1.69 eV. FESEM analysis showed porous structures for Co3O4 and agglomerated nanoparticles for ZnO-Co3O4. Under UV irradiation, ZnO-Co3O4 nanocomposites showed superior performance, achieving 83.46 %, 99.78 %, and 98.65 % degradation for CR, MB, and RhB dyes in 100, 100, and 60 min, respectively. The Langmuir-Hinshelwood model revealed significantly higher rate constants for ZnO-Co3O4 nanocomposites compared to Co3O4 nanostructures, with improvements of 3.274, 2.042, and 4.917 times for CR, MB, and RhB dyes. These findings highlight the potential of these nanocomposites as effective photocatalysts for environmental remediation.