Sulfide ZnS-SiO2 composite photocatalysts with biogenic silica matrix were prepared by sol-gel method based on wet gel and xerogel. FT-IR, SEM, XRD, EDXRF, UV-Vis, and XPS methods were systematically used to characterize the obtained materials. The use of support allowed to obtain stable porous (SBET = 79-105 m2g-1; Vpore = 0.25-0.17 cm3·g-1) ZnS-SiO2 photocatalysts in aqueous solutions. Zn2+ content in methyl orange solution after its degradation was 0.4 MPC. ZnS-SiO2 composites had 3.68-3.70eV band gap. The obtained materials were photoactive under different irradiation conditions (sunlight, UV-light, Xenon light, visible light) due to effective separation of charge carriers (e- and h+). Methyl orange degradation degree under UV light excitation was 35-88%, under sunlight - 11-30%. ZnS-SiO2 composite synthesized using silica xerogel showed a greater photoactivity due to a presence of cone-shaped or cylindrical pores with one open end in its structure and a higher content of ZnS photoactive component. A comparative study of photocatalytic performance of methyl orange degradation by ZnS-SiO2 under UV irradiation was investigated using radical scavengers. •O2- was main active species during MO degradation under UV irradiation, and electrons played additional role during the photocatalytic process.