In this study the impact of temperature and metal contamination on the stability of hydrogen peroxide in the two most common wet chemical cleaning mixtures for wafer process operations has been investigated. The stability of the caustic mixture ( NH4OH/H2O2/H2O) was found to be very sensitive to certain metallic contaminations in the sub-ppb range, while the stability of the acid mixture ( HCl/H2O2/H2O) is mainly influenced by non metallic, anionic components of the solution itself. We observed also a strong oscillating behaviour of the rate of the oxygen gas evolution caused by the decomposition of H2O2. Furthermore it was found, that the oxygen gas bubbles, formed by the decomposition of hydrogen peroxide cause a certain kind of micro-roughness on the silicon surface through a micro masking mechanism. In a series of experiments we could prove that this kind of surface roughness has a significant impact on the integrity of thin gate oxides.