The temperature of cities continues to increase because of the heat island phenomenon and the undeniable climatic change. The observed high ambient temperatures intensify the energy problem of cities,deteriorate comfort conditions, put in danger the vulnerable population and amplify the pollution problems. Now mitigation techniques aim to balance the thermal budget of cities by increasing thermal losses and decreasing the corresponding gains. Among the more important are those targeting to increase the albedo of the urban environment, to expand the green spaces in cities and to use the natural heat sinks in order to dissipate the excess heat. The objective of the lecture is to review, in a critical way, the available scientific information on the mitigation.