Study on availability and reliability of electric chillers (EC) at a co-generated district cooling plant using Markov model is presented in this paper. Five years performance data were used to determine the states of the models covering the full working, partial working and failed states. State space diagram is used to indicate the possible operating scenario of the EC. The differential equations were formulated to evaluate the availability and reliability of the chilled water generated by the EC. Results from the analysis indicate that the model is able to predict the EC availability with 95 per cent confidence level in comparison with the actual data. While for the case of reliability, the values obtained by the model are comparable with the traditional binary reliability. In conclusion the developed models could be useful to predict the availability and reliability of EC at the district cooling plant. © 2011 IEEE.