weight of the hydrogen peroxide in the solution contrary to the teaching of the prior art neither the use of crude hydrogen peroxide solutions obtained from the anthraquinone process without carefully controlling the amount of alkali metals and amines having a pk b below 4 5 nor the use of purified hydrogen peroxide solutions where in addition to the metal cations also the stabilizing anions have been removed are suitable for an economical process for epoxidation of olefins although an amount of alkali metals or alkaline earth metals of less than 50 wppm based on the weight of hydrogen peroxide in the solution is acceptable it is preferred to reduce the amount of these components to be less than 40 wppm more preferred less than 35 wppm in order to further improve the long term activity and selectivity of the catalyst so far in the literature the detrimental effect on amines having a pk b of less than 4 5 on the long term selectivity and activity of an epoxidation catalyst has not been recognized the effect of the presence of such amines is even more pronounced than the effect of the alkali metals or alkaline earth metals therefore it is particularly preferred to reduce the amount of amines having a pk b of less than 4 5 in the aqueous hydrogen peroxide solution in total to less than 40 wppm preferably less than 30 wppm more preferably less than 20 wppm and most preferably less than 10 wppm based on the weight of hydrogen peroxide.