Abstract Results on the studies of dielectric properties of the chicken egg membrane deposited with CdS nanoparticles are presented in this article. The CdS nanoparticles are synthesized in the membrane by the diffusion of the precursor solutions of cadmium acetate and thiourea across the membrane. The AC capacitances of the membrane were measured in the frequency range of 1 kHz–10 MHz. The capacitance of the membrane drops in the entire frequency range of measurement with the deposition of CdS nanoparticles and the extent of the drop being dependent on the reaction parameters. Drop in capacitance is highest for conditions favoring small nanoparticles. The drop in capacitance with the deposition is attributed to the presence of Cd(OH) 2 in the deposits. The volume fraction and capacitance of that component of the deposit responsible for reducing the capacitance of the deposited membrane below that of the undeposited could be estimated by assuming a simple model. X-ray photoelectron spectra (XPS) of the deposited membrane indicate that nanoparticles of CdS are not formed on the surface but formed deep in the pores of the membrane. These particles are found to be cadmium rich, thus supporting the inference that the Cd(OH) 2 is formed along with the CdS nanoparticles.