An outburst of coal and gas is a major hazard in underground coal mining. It occurs when certain conditions of coal stress, strength and gassiness are met. The outburst is recognized as a two-step process, i.e. initiation and development. Each step has its own characteristics and requires different approaches in numerical modeling. As a first step, the initiation process of the outburst is numerically simulated with a coupled simulator. The simulator models the deformation and failure of a coal seam, adsorption and desorption of gas and flow of gas and water in coal. The simulator is developed by linking and sequentially executing two numerical codes: FLAC3D and COMET3. FLAC3D is a widely used commercial code designed for engineering mechanics computation, while COMET3 is a well-established code to model gas and water production from desorption-controlled reservoirs. In this paper, these two codes are linked and sequentially executed through coupling modules including a user-designed C++ module and several modules developed with the build-in FISH language in FLAC3D. These coupling modules are used to transfer relevant data between the codes. A simple example to simulate the initiation of the outburst is also presented in this paper to demonstrate the capability of the coupled simulator. (C) 2011 Elsevier B.V. All rights reserved.