Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)This review provides an overview of the use of mass spectrometry (MS) and its various ionization techniques and an evaluation of their suitability to investigate structures and physico-chemical properties of ionic liquids (IL) and the types of information that can be obtained from such experiments. We will focus on most representative and comprehensive work, and on the work that we are been performing in an collaboration involving our laboratories, one devoted to the synthesis and uses of IL and to the other to the development of new MS techniques and their applications.173257272Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)FINEPFAPERGSINCTsFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)