A process for the hydroisomerization of a predominantly C.sub.8 -C.sub.20 n-paraffinic feed to produce a high purity C.sub.8 -C.sub.20 paraffinic solvent composition having superior low temperature properties, and low viscosities. The feed is contacted, with hydrogen, over a dual functional catalyst to hydroisomerize and convert the feed to a product comprising a mixture of n-paraffins and isoparaffins, the isoparaffins component of which contains greater than 50 percent of mono-methyl species, with the molar ratio of isoparaffins:n-paraffins ranging from about 0.5:1 to 9:1.