A passive, air-breathing polymethyl methacrylate (PMMA) based single-cell and a multi-cell stack micro-direct methanol fuel cell (DMFC) with 1.0 cm(2) active area with a novel cathode plate structure and assembly layer are designed, fabricated and tested. The fuel cell is completely passive with no auxiliary device such as pump or fan. Oxygen is taken from the surrounding air, and the methanol solution is stored in a built-in reservoir. The performance of the single cell is tested with different methanol concentrations ranging from 1.0 M to 5.0 M, and the optimum performance is achieved by using methanol at a concentration of 4.0 M. A stack with 6 cells is fabricated and tested with the optimum methanol concentration of 4.0 M, and power levels produced by different catalyst loadings on the anode are compared. Besides, this study also considers the cost analysis of micro-DMFC. The combination of a catalyst loading of 3.0 mg cm(-2) Pt/Ru on the anode and 2.0 mg cm(-2) Pt on the cathode yield the highest power of 12.05 mW at 1.08 V and 11.2 mA. The total cost for the micro-DMFC in this study is only about USD 2 mW(-1). (c) 2009 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.