A hybrid direct carbon fuel cell (HDCFC), combining molten carbonate fuel cell MCFC and solid oxide fuel cell (SOFC) technologies, is capable of converting solid carbon directly into electrical energy without intermediate reforming. The performance level achieved on small-scale cells (area <4 cm(2)) suggests that engineering developments should now be undertaken to scale up and demonstrate the feasibility of practical systems. The scaling up of the HDCFC through the design and test of single stack repeat unit with realistic cell sizes was investigated in this study. A single cell of similar to 12.56 cm(2) active area produced a maximum power of similar to 1.2 W at 800 degrees C and a current density of similar to 200 mA cm(2) at 0.6 V, using wood-based pyrolyzed medium density fiberboard (p-MDF) as fuel. In comparison, the HDCFC with activated carbon as fuel produced a maximum power density of 36 and 53 mW cm(-2) at 700 and 800 degrees C, respectively, and an electric efficiency of similar to 40% evaluated under 0.7 V for 17 h at 700 degrees C. These results demonstrated the applicability of HDCFC to practical systems while stack units were operated in batch mode and an appropriate fuel feeding mechanism has to be designed. Moreover, more engineering advances should be done to enhance power output since a HDCFC stack unit involves multiple challenges that have not been addressed yet, including system configuration and corrosion protection, and durability. Copyright (C) 2012, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.