The objective of this study is to develop a model to determine the thermal conductivity of pure ionic liquids and Ionanofluids. In order to estimate the thermal conductivity of pure ionic liquids, a group method of data handling model is proposed based on 23 ionic liquids corresponding to 216 experimental data points.The average absolute relative deviation for all studied systems was 1.81%, which is a satisfactory degree of accuracy for the proposed model. Furthermore, the Maxwell model is modified to correlate the thermal conductivity of Ionanofluids as a function of temperature and volume fraction of nanoparticles. The average absolute relative deviation for this model is 0.61%. Additionally, Maxwell and modified geometric mean (mGM) models are used to evaluate the models that * Corresponding predict the thermal conductivity of Ionanofluids. The results show that mGM is more accurate for prediction of thermal conductivity of Ionanofluids.