The effect of diffusion layer compression on the passive direct methanol fuel cell (DMFC) performance has been investigated experimentally. The teflonized carbon cloth with micro-porous layer has been used as diffusion layer. The cell performance has been evaluated for different compression ratios of the diffusion layer and for different methanol feed concentrations. The polarization test, open circuit voltage test and scanning electron microscopy are performed in this connection. It is found that the diffusion layer compression has significant effect on the passive DMFC performance. The under-compression and over-compression leads to inferior cell performance and the cell performance is optimum at a particular value of diffusion layer compression. In this study, the passive DMFC with 4M methanol feed concentration and 32.5% compression ratio gives optimum performance. This study reveals that the cell performance can be enhanced drastically (200% to 340% higher) by using the optimum diffusion layer compression. In view of this, it is recommended to control the diffusion layer compression precisely during assembling of passive DMFC. (C) 2014 Elsevier Ltd. All rights reserved.