Miscible gas injection (MGI) processes such as miscible CO2 flooding have been in use as attractive EOR options, especially in conventional oil reserves. Optimal design of MGI is strongly dependent on parameters such as gas-oil minimum miscibility pressure (MMP), which is normally determined through expensive and time-consuming laboratory tests. Thus, developing a fast and reliable technique to predict gas-oil MMP is inevitable. To address this issue, a smart model is developed in this paper to forecast gas-oil MMP on the basis of a feed-forward artificial neural network (FF-ANN) combined with particle swarm optimisation (PSO). The MMP of a reservoir fluid was considered as a function of reservoir temperature and the compositions of oil and injected gas in the proposed model. Results of this study indicate that reservoir temperature among the input parameters selected for the PSO-ANN has the greatest impact on MMP value. The developed PSO-ANN model was examined using experimental data, and a reasonable match was attained showing a good potential for the proposed predictive tools in estimation of gas-oil MMP. Compared with other available methods, the proposed model is capable of forecasting oil-gas MMP more accurately in wide ranges of thermodynamic and process conditions. All predictive models used other than the PSO-ANN model failed in providing a good estimate of the oil-gas MMP of the hydrocarbon mixtures in Azadegan oilfield, Iran. (c) 2013 Canadian Society for Chemical Engineering