Synthesis, characterization, and the optical behavior of CdS quantum dots nanoparticles were stud-ied confined in clays. An alternative synthesis approach in different natural clays K-10 bentonite, Na-montemorillonite, halloysite, and saponite was carried out. The composite materials were char-acterized by XRD and FTIR spectroscopy, energy dispersive, scanning, and transmission electron microscopy. After CdS-QDs formation, the synthesized materials became fluorescent with emis-sion wavelengths (average and standard deviation of the maximum wavelength; full width of half maximum): K-10 bentonite-CdS (590 AE 5 nm; 183 nm); Na-montmorillonite-CdS (550 AE 3 nm; 219 nm); saponite-CdS (550 AE 5 nm; 219 nm), and halloysite-CdS (590 AE 8 nm; 185 nm).