We have newly prepared protic ionic liquids (PIL) composed of monoprotic alkylethylenediaminium (alkyl = N-hexyl and N-2-ethylhexyl) cations coupled with bis(trifluoromethanesulfonyl)amide anion (=TFSA) at room temperature. It is in contrast to the monoprotic N-hexylethylenediaminium (=HexH)TFSA salt which tends to crystallize on cooling that the monoprotic N-(2-ethylhexyl)ethylenediaminium (=EtHexH)TFSA salt assumes only a glassy state in solid. In the liquids, the HexH salt is more fluid than the EtHexH salt.