This final report describes the results of a study for the US Department of Energy to prepare a Conceptual Design of an Integrated Gasifier Combined Cycle (IGCC) Power Plant. The study was conducted by a team of organizations to provide the necessary information for the diverse systems which make up an IGCC plant. The operating characteristics, reliability and cost estimates for the fuel preparation train, including the Texaco gasifier, were prepared by Bechtel Group, Inc. Similar information for the gas turbine system was provided by United Technologies Corporation. System optimization and steam system characteristics were developed jointly. The overall power plant designs were prepared by Bechtel. Niagara Mohawk Power Corporation provided utility view points and consultation as well as a specific site location. United Technologies managed the contract. Conceptual designs were prepared for a grass roots plant and repower configuration. A demonstrator plant for verification of concepts was configured, including a development plan and associated costs.