The most important disadvantage of copper based preservatives is low copper fixation on wood components. This is an important drawback, when impregnated wood is used in conditions where leaching of active components is possible. Copper fixation used to be improved with the addition of chromium compounds. Nowadays, it is mainly combined with ethanolamine and octanoic acid. It has already been proven that ethanolamine reacts with wood and copper, resulting in improved Cu fixation. On the other hand, octanoic acid has hydrophobic mode of action. In order to optimize the composition of copper-ethanolamine based wood preservative, influence of pH value on copper leaching was examined. To elucidate those questions, specimens made of Norway spruce were impregnated with different aqueous solutions on the basis of copper, ethanolamine, octanoic acid, quaternary ammonium compounds and boron. Leaching was performed according to the modified standard procedure SIST EN 1250/2. Copper content in leachates was determined using atomic absorbtion spectroscopy. Specimens impregnated with the solutions of lower copper concentration (cCu = 0.1 %) were less prone to leaching than the ones impregnated with specimens of higher concentration (cCu = 0.5 %). Besides that, pH value of preservative solution has significant influence on copper fixation as well. In general, the best fixation was determined at specimens impregnated with copper-ethanolamine solutions of the lowest, the least alkaline pH values.