Abstract: Individual micrometer-size particles of inorganic nitrogen salts, such as NaNO3, NaNO2, (NH4)2SO4, NH4Cl, NH4NO3 and their mixtures, were analysed in the laser microprobe mass analyser. The cluster-ion distributions of the salts are systematically described and can be used to gain speciation information. The results can be used to study the distribution of the atmospheric aerosol inorganic nitrogen compounds and to investigate their chemical transformations under ambient conditions.