Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF-MS) was utilized for the analysis of polymers obtained by the living cationic polymerization of isobutyl vinyl ether (IBVE) with the HCl-VE adduct/SnCl4/n-Bu4NCl initiating system in CH2Cl2 at -78 degreesC. Under optimized analysis conditions, well-resolved spectra were obtained for samples with number-average molecular weights of less than or equal to 10(4) with the use of 1,8-dihydroxy-9(10H)-anthracenone (dithranol) as a matrix and sodium trifluoroacetate as an added salt. The MS spectra showed only one series of peaks separated exactly by the mass of the IBVE. The observed mass of each peak was in good agreement with the theoretical one, which possesses one initiator fragment at the alpha end and one methoxy group originated from quenching with methanol at the omega end. Thus, detailed end group analysis is possible for poly(VE).