The Technology Acceptance Model was extended to explain the acceptance of mobile devices. The technological characteristics of mobile devices and trust were hypothesised as predictors of mobile device usage. The study of 212 mobile users indicate that device service reliability does influence perceived trust, perceived ease of use, and perceived usefulness, while device interface quality only predicts perceived trust and perceived ease of use. The findings suggest that trust and mobile device characteristics play essential roles in the acceptance of mobile device usage, and need to be incorporated into the design of future mobile commerce applications.