The deactivation of a 15 wt.% Ni supported on SiO2 (15 NiSi) catalyst by triphenylphosphine during the hydrogenation of octanal to octanol, and subsequent regeneration, was studied. Characterization of the catalyst by hydrogen chemisorption, TPR, powder XRD, ICP-OES, BET surface area analysis, and TEM showed the presence of large nickel clusters with a poor metal dispersion for the fresh catalyst prior to deactivation. This, however, had a positive effect, since the catalyst was very active and highly tolerant of the triphenylphosphine poison, taking significantly longer on stream to deactivate compared to a 15% Ni supported on alumina catalyst (15 NiA). The 15 NiSi catalyst was also effectively regenerated using a tandem octanol wash-hydrogen treatment regeneration protocol, which restored the conversion to 76%, after deactivation to 20%, and restored the octanol selectivity to that observed for the non-poisoned 15 NiSi catalyst, which was 86%. The present catalyst was also shown to be more effectively regenerated when compared to the 15 NiA catalyst. Regeneration of the poisoned catalyst did not remove phosphorus, but restored large nickel particles and resulted in the formation of Ni2P, which is active for octanal hydrogenation.