Contact-time　measurements　based　on　sites　are　used　to　investigate　the　reaction　sequence　of　the　hydrodeoxygenation　of　gamma-valerolactone　(GVL)　on　Ni2P/MCM-41.　The　study　is　carried　out　at　300　degrees　C　and　0.5　MPa　with　site　times　of　0.29-6.1　s.　A　reaction　network　is　proposed　in　which　pentanoic　acid　and　2-methyltetrahydrofuran　(2-MTHF)　are　formed　in　parallel　initially　and　pentanal,　butane　and　pentane　are　formed　subsequently.　A　first-rank　Delplot　analysis　(selectivity)　gives　a　good　fit,　but　higher-rank　Delplots　do　not.　The　lack　of　applicability　is　explained　by　the　magnitude　of　the　rate　constants,　in　which　the　rate　constant　for　one　of　the　later　steps　(the　consumption　of　pentanal)　is　substantially　larger　than　those　for　the　preceding　steps.　For　this　reason,　pentanal　demonstrated　the　characteristics　of　a　primary　product　and　consequently　affected　the　discrimination　of　higher　rank　products.　A　simulation　of　a　model　sequence　with　assumed　rate　constants　confirms　the　reason　why　the　Delplot　method　does　not　work　for　this　reaction.　Since　the　rate　constants　cannot　be　determined　a　priori　to　be　of　close　magnitude,　the　Delplot　method　cannot　be　generally　used　to　ascertain　reaction　sequences.　(C)　2020　Elsevier　Ltd.　All　rights　reserved.