The objective of this study is to elucidate the effects of MgO promotors on the catalytic physico-chemical properties of Ru/gamma-Al2O3 catalysts and the activity during the tricyclopentadiene (TCPD) hydrogenation reaction. Ru/gamma-Al2O3 and Ru-MgO/gamma-Al2O3 catalysts were produced by means of a coprecipitation method and formed in a bead type. The specific surface area of the regenerated Ru-MgO/gamma-Al2O3 catalyst is much larger than that of the regenerated Ru/gamma-Al2O3 catalyst. It was confirmed that the addition of MgO has the effect of alleviating the decrease of the specific surface area during the repetitive regeneration procedure. The addition of MgO had no significant effect on the reducibility of the Ru/gamma-Al2O3 catalyst. The results of XRD, CO chemisorption and TEM imagery show that the addition of MgO to the Ru/gamma-Al2O3 catalyst has the effect of decreasing the mobility of Ru atoms during repetitive regeneration at 650 degrees C. It was confirmed that the degree of catalyst deactivation during four repetitive regeneration trials was much lower than that with an unpromoted catalyst, likely because the addition of MgO prevented the sintering of Ru at the regeneration temperature of 650 degrees C. The Ru-MgO/gamma-Al2O3 catalyst is a possible candidate as a reusable catalyst for use during the TCPD hydrogenation reaction.