Disclosed is a process for producing phenol or a substituted phenol and a co-product comprising the steps of (i) contacting a first stream comprising an alkylaromatic compound with a second stream comprising an oxygen-containing gas in the presence of a first catalyst comprising a cyclic imide under conditions to convert at least a portion of said alkylaromatic compound to an alkylaromatic hydroperoxide, (ii) producing an effluent stream comprising said cyclic imide, said alkylaromatic hydroperoxide, and said alkylaromatic compound wherein said effluent stream has an alkylaromatic hydroperoxide concentration of from 10 to 40 wt %; and (iii) contacting in a second reactor at least a portion of said effluent stream with a second catalyst to convert said alkylaromatic hydroperoxide to a product stream comprising phenol and said co-product.