We synthesized organically modified silicate microparticles, known as diphenyl silicate (DPS), and showed that the synthesized DPS has a nano-layered microstructure. We utilized this material as a filler for fabricating Nafion (R)vertical bar DPS composite membranes for mitigating the problem of methanol crossover in direct methanol fuel cells (DMFC). The SEM and XRD analyses indicated that the incorporated DPS microparticles were uniformly distributed in the native membrane. The DMFC performance tests demonstrated that the use of the Nafion (R)vertical bar DPS composite membranes resulted in a lower rate of methanol crossover, higher open-circuit voltage (OCV) and better cell performance than did the pure Naflon (R) membrane, especially with a higher methanol concentration such as 10 M. (c) 2006 Elsevier B.V. All rights reserved.