Abstract : Atmospheric aerosols are found everywhere and have a strong impact both at a global scale, through their role in the radiative balance of the Earth, and at local scale, through the related public health issue in strongly polluted zones. The organic matter is one of the major components of the aerosol. Its complexity and heterogeneity still make its integration in medical or climatic impact studies difficult. About 10 to 30% of the mass of the organic fraction is made of “Humic Like Substances”. The aim of this thesis is to develop a reliable method of extraction and analysis of the HULIS (HUmic LIke Substances) resulting from the atmospheric aerosol. The purpose is also to determine their spatial and temporal distributions, their major sources and their chemical structures based on 250 samples collected at six urban sites. Identification of the two major sources of HULIS in the aerosol, secondary sources (like photo-oxidation in aqueous phase) in summer and the primary sources related to combustion of biomass in winter, and this, independently of the location is shown. A significant difference between the chemical structure of HULIS coming from these two major sources is observed: they gather more aliphatic and less aromatic compounds in summer than in winter, and their content of carboxylic groups increases from wintertime to summertime.