Through the extensive R&D effort for heavy oil upgrading technology in Japan Petroleum Cooperation Center, Petroleum (JCCP) since 1993, a zeolite-based new catalyst for atmospheric resid (AR) hydrocracking was developed. Its production in industrial scale was successfully accomplished, and its high and stable performance as resid hydrocracking catalyst in Atmospheric Resid Desulfurization (ARDS) unit was confirmed in bench plant using Kuwait atmospheric resid (Kw-AR) as feed. Namely, toward 2600 h of duration, AR conversion and middle distillate yield were stable at 47% and 30 wt%, respectively, and products quality was excellent, such as cetane index of diesel fraction was very high, as high as 56, and its sulfur content was about 30 ppm, which was by far the lower compared to conventional ARDS unit. (C) 2004 Elsevier Ltd. All rights reserved.