A linear relationship represents the hydrogenation activity decay of catalysts used in four experimental runs reported previously. The weight percent hydrogen in the reactor product oils plotted against oil-catalyst contact time for experimental runs ZBB, ZBC, ZBD, and ZBE reveals a linear decay rate of 0.0083 wt% hydrogen per hour. This is one quantitative measure of catalyst activity decay. The data for the plot incorporate three different catalysts or combinations used to process a PAMCO liquid at 1500 psig, 435C and LVHST of 2 hours. The data set covers run duration of up to 120 hours of oil-catalyst contact. An air driven hydrogen compressor was installed in the Catalyst Life Test Unit to reduce the costs associated with bottle hydrogen. Minor repairs were made on the oil feed pump. Five experimental runs were made with Shell 324 NiMo/Al catalyst using two feedstocks: (1) 40 wt% EDS/EDS raw solvent and (2) 30 wt% SRC-I creosote oil. The EDS feed oil proved to be rather easily hydrotreated as evidenced by 82 to 100% nitrogen removal, essentially complete desulfurization and no catalyst activity decay during 260 hours of continuous operation. Rapid coking resulted from the highly hydrogen deficient SRC/creosote mixture. The Shell 324 catalyst gave excellent hydrogenation of both liquids by increasing the hydrogen content of the product oils by about 3.8 wt%. This catalyst will be used in future studies; however, a new feedstock consisting of 30 wt% SRC-I/PAMCO process solvent will be assessed for use in catalyst decay mechanism studies.