In　the　slurry-phase　hydroconversion　to　produce　biofuels,　the　reaction　mechanism　for　hydrodeoxygenation　of　long-chain　unsaturated　olefinic　acids　is　still　unclear.　Here,　MoS2　was　in-situ　generated　during　reaction　using　molybdenum(IV)　2-ethylhexanoate　as　the　oil-soluble　precursor.　The　generated　MoS2　was　identified　with　1　T　(or　1　T’)　phase　rather　than　2H　phase　based　on　Raman　and　EXAFS　analysis.　It　is　found　that　the　hydrogenation　of　monounsaturated　bonds　firstly　takes　place,　followed　by　the　hydroconversion　of　carbonyl　groups.　Wax　esters　are　then　produced　as　the　heavy　by-products　with　up　to　∼69.3　%　yield　at　290　℃,　however,　it　can　be　quickly　consumed　above　310　°C.　Based　on　the　in-situ　FTIR　and　DFT　results,　the　consumption　of　acids　and　formation　of　wax　esters　was　distinctly　illustrated.　The　C-O　bond　of　the　monodentate　ester-type　acid　dissociates　to　form　acyl　group,　which　is　then　hydrogenated　to　form　alkoxide,　and　they　are　finally　combined　to　generate　wax　esters.　©　2025　Elsevier　Ltd