(Vapour + liquid) and (liquid + liquid) equilibria for (water + p-xylene) and (water + decalin) mixtures at T = (573 to 623) K were measured by a flow type apparatus with microfluidic system. The liquid-liquid slug flows in the microfluidic system were used for mixing of water and hydrocarbon due to high mass transfer between two liquid phases. The formations of the liquid-liquid slugs for (water + p-xylene) system were studied by changing the flow rate. The results of the liquid-liquid slug formations at hydrocarbon and water rich compositions were used for the measurements for (vapour + liquid) and (liquid + liquid) equilibria, respectively. It was found that the phase equilibria using the apparatus with the microfluidic system can be measured in a short residential time (1.6 to 3.2) min. The experimental results of the phase equilibria for (water + p-xylene) and (water + decalin) systems give that the regions of the (vapour + liquid) and (liquid + liquid) equilibria for both mixtures reduce with the increasing temperature. The mixture of (water + decalin) at T = (583 to 623) K forms the two phase regions of the (vapour + liquid) and (liquid + liquid) equilibria larger than those for (water + p-xylene) mixture. The experimental data of the phase equilibria obtained in this work were correlated with Peng-Robinson-Stryjek-Vera equation of state. The correlated results of the (liquid + liquid) equilibria for both systems represent the experimental data. For (vapour + liquid) equilibria, the results give the qualitative representations in the shape of the two phase region for both mixtures. (c) 2012 Elsevier Ltd. All rights reserved.