A method of catalytically hydroconverting a hydrocarbon feed stream containing a substantial quantity of components boiling above about 1000.degree. F. to convert a substantial portion thereof to components boiling below 1000.degree. F. is disclosed. More particularly, aromatic heavy oil additive, such as Heavy Cycle Gas Oil, is added to a heavy hydrocarbon feed stream and the stream is contacted with a solid catalyst and an oil-miscible metal naphthenate. The method disclosed herein advantageously substantially eliminates plugging of the hydroconversion reactor and minimizes the amount of insolubles in the total liquid product.