Galaxy clusters allows us to investigate cosmology and in particular the properties of dark energy. In this talk I will describe AMICO (Adaptive Matched Identifier of Clustered Objects), a new code for the detection of Galaxy Clusters in photometric wide field surveys. AMICO is going to be implemented in the data analysis pipeline of the Euclid ESA space mission. This code takes advantage of the statistics of the color, luminosity and photometric redshift of the galaxies belonging to the field and those belonging to clusters. These initial statistical properties are refined through an iterative approach which takes advantage of the newly detected objects. Its construction allows to maximize the signal-to-noise ratio of the structures to be found. In addition it returns a mass proxy for the detected galaxy clusters and a probabilistic association of the galaxies to these structures, a very useful information for the study of the precious objects.