The formation and characterization of CdS nanoparticles embedded within Langmuir-Blodgett films are described. CdS nanoparticles were formed within calyx arene (CA) and stearic acid (SA) Cd-salt LB films by exposure to H2S gas at room temperature. The AFM images of the treated SA and CA bilayers show CdS clusters with lateral dimensions. These particles are pseudo two-dimensional and have a shape of hexagonal platelets. The transformations of the absorption spectra by ageing yield a monotonic increase in CdS cluster size with the tendency of saturation. This behaviour is modeled with two dimensional diffusions. The Surface Plasmon Resonance and ellipsometry measurements confirmed the H2S treatment to the LB films results in the increase in thickness and refractive index of the LB films due to formation of CdS nanoparticles inside. The sandwich structures of Aluminium/LB films/ Aluminium show exponential behaviour and weak temperature. The CdS clusters did not result an enhancement of the electron transfer or an additional polarisation at a small AC signal, the changes in DC conductivity and AC impedance are due to the film disorder by CdS nanoparticles.