Mathematical models of direct internal reforming solid oxide fuel cell (DIR-SOFC) fueled by methane are developed using COMSOL (R) software. The benefits of inserting Ni-catalyst rod in the middle of tubular-SOFC are simulated and compared to conventional DIR-SOFC. It reveals that DIR-SOFC with inserted catalyst provides smoother temperature gradient along the system and gains higher power density and electrochemical efficiency with less carbon deposition. Sensitivity analyses are performed. By increasing inlet fuel flow rate, the temperature gradient and power density improve, but less electrical efficiency with higher carbon deposition is predicted. The feed with low inlet steam/carbon ratio enhances good system performances but also results in high potential for carbon formation; this gains great benefit of DIR-SOFC with inserted catalyst because the rate of carbon deposition is remarkably low. Compared between counter- and co-flow patterns, the latter provides smoother temperature distribution with higher efficiency; thus, it is the better option for practical applications. (C) 2009 American Institute of Chemical Engineers AIChE J, 56: 1639-1650, 2010