In this paper, an exergy cost analysis method based on the structural theory of thermoeconomics is applied to a gas-fired micro-trigeneration system, which uses a small-scale generator set driven by a gas engine and a new small-scale adsorption chiller (ADC). The thermoeconomic model for the system based on the fuel-product concept is defined to quantify the productive interaction between various components. The distribution of the resources and costs of all flows in the productive structure are calculated by solving a set of equations according to the experimental data. By adopting the exergy cost analysis method, the production performance of components at design and variable conditions of combined cooling and power are evaluated in detail. Moreover, a comparison between the method of conventional exergy analysis and exergy cost analysis is presented. The results not only reflect that the structural theory is a powerful and effective tool for performance evaluation of complex system, but also prove that the micro-trigeneration system is efficient in utilizing the low-grade waste heat. (C) 2008 Elsevier Ltd. All rights reserved.