Abstract: The effect of temperature and pH on the adsorption of hen egg white lysozyme on silica and polystyrene interfaces has been studied using optical spectrometer. The adsorption density has been determined over a temperature range with protein solution concentrations ranging from 0.10 to 1.40 g L-1. It has been found that the amount of adsorbed protein is strongly increased by an increase in temperature, which indicates an endothermic and thus an entropy-driven adsorption process. This can be explained by an adsorption-induced modification of the protein conformation. At high temperatures, where dissolved lysozyme is mainly unfolded, hydrophobic dehydration effects will as well play a role. The results support the concept that thermodynamically unstable proteins adsorb more strongly at interfaces than stable proteins. However, the maximum adsorption of lysozyme on both surfaces occurred at a pH range of 10.0 to 12.0, which peaked at 11.0 with adsorption densities of 12.082x10-9 mol m-2 for silica and 5.879x10-9 mol m-2 for polystyrene. This behavior showed that lysozyme has maximum adsorption within its isoelectric point of pH 11.0. The spectra of the adsorbed lysozyme were observed for varying temperature values on the two surfaces. The spectra showed maximum absorbance of 0.8020 at 20°C for silica and 0.7860 at 50°C for polystyrene at the same wavelength of 500 nm. The minimum absorbance occurred at the same wavelength of 600 nm and temperature of 40°C corresponds to the minimum absorbance of 0.004 for silica and 0.028 for polystyrene. Comparatively, minimum absorbance occurred at the same wavelength and temperature for both surfaces, but in contrast, maximum absorbance, though occurred at the same wavelength, but different temperatures; a phenomenon attributed to the non-synthetic nature of silica and synthetic nature of polystyrene surfaces.