To provide a process for the simple cleavage of cumene hydroperoxide in high safety at a low investment cost and in high usefulness due to the avoid of adhered products without carrying out the original post treatment of the cleaved product produced by the cleavage of the cumene hydroperoxide into phenol and acetone in the presence of an acid catalyst.

This process for the cleavage of alkylaryl hydroperoxides in the presence of an acid catalyst comprises the steps of producing a mixture of a concentrate that contains at least one alkylaryl hydroperoxide to be cleaved and a cleavage product obtained form the cleave of an alkylaryl hydroperoxide, dividing this mixture into at least two parts and cleaving the alkylaryl hydroperoxides in parallel at different temperatures.