Four new 1-dodecyl-1-methylpirydinium (I) salts were synthesized by conversion of the I bromide in H2O or MeOH to resp. I methylsulfate, formiate, acetate or metoxyacetate (yield 98-99%). The I salts (ionic liqs.) were studied for structure by H-1 NMR and C-13 NMR spectroscopy and for electrolytic cond. to dot. crit. micelle concns. and free energy of micellization. Three solid 1-R-1-methylpiperidinium bromides (R = C-8, C-10 and C-12 alkyl) were also studied for crit. micelle concn. and free energy of micellization.