The physicochemical and electrochemical properties of the water-soluble, N-methoxyethyl-N-methylpyrrolidinium trifluoromethanesulfonate (PYR1(2O1)OSO2CF3) ionic liquid (IL) were investigated and compared with those of commercial N-butyl-N-methylpyrrolidinium trifluoromethanesulfonate (PYR14OSO2CF3). The results have shown that the transport properties are well correlated with the theological and thermal behavior. The incorporation of an oxygen atom in the pyrrolidinium cation aliphatic side chain resulted in enhanced flexibility of the ether side chain, this supporting for the higher ionic conductivity, self-diffusion coefficient and density of PYR1(2O1)OSO2CF3 with respect to PYR14OSO2CF3, whereas no relevant effect on the crystallization of the ionic liquid was found. Finally, the presence of the ether side chain material in the pyrrolidinium cation led to a reduction in electrochemical stability, particularly on the cathodic verse. (C) 2013 Elsevier Ltd. All rights reserved.