A miniature air breathing compact direct formic acid fuel cell (DFAFC), with gold covered printed circuit board (PCB) as current collectors and back boards, is designed, fabricated and evaluated. Effects of formic acid concentration and catalyst loading (anodic palladium loading and cathodic platinum loading) on the cell performance are investigated and optimized fuel concentration and catalyst loading are obtained based on experimental results. A maximum power density of 19.6 mW cm(-2) is achieved at room temperature with passive operational mode when 5.0 M formic acid is fed and 1 mg cm(-2) catalyst at both electrodes is used. The home-made DFAFC also displays good long-term stability at constant current density. (C) 2010 Elsevier B.V. All rights reserved.