Green roofs provide environmental benefits by protecting buildings against solar radiation and temperature fluctuations and by reducing building's energy consumption by direct shading. Our objective was to evaluate for the first time the performance of an extensive green roof in Reunion Island (Indian Ocean) influenced by a tropical humid climate. The green roof performance was explored by evaluating its effect on temperature fluctuations and heat fluxes during the summer season. The results showed that the presence of plants led to a decrease in temperature under the green roof. Plants also contributed to a lower heat flux exchange through the green roof. The determination of major parameters including U-value, R-value and k-value, demonstrated the thermal and energetic behavior of the green roof and helped to highlight Sedum plant benefits. To conclude, this study has demonstrated the thermal and energetic performance of a green roof based in an area under a tropical humid climate.