The emerging need for rapid screening and identification methods for microbiological purposes necessitates the combined uses of high-tech instruments. In this work, electrospray ionization mass spectrometry was used to visualize the relation of ten newly isolated moderately halophilic microorganisms, to Halomonas salina DSMZ 5928 and Halomonas halophila DSMZ 4770. The method was based on the global analysis of the metabolites in culture media and is termed as metabolic footprinting. Since it was not possible to gain insight into the similarities solely based on the visual inspection of the chromatograms, principal component (PC) analysis was applied on the data. Three PCs alone were able to explain 99% of the information in the data set. The score plots revealed the relation of the new isolates to the two type strains whereas the loading plots gave important clues on the significant ions responsible for the observed clustering. Loading plots also indicated inversely correlated ions that give clues on differing metabolic pathways. The work described here offers a potentially useful way for preliminary rapid phenotypic characterization of new and closely related isolates and a method for screening of similar microorganisms for different and valuable secondary metabolites.