The continuing increase of interest in ionic liquids prompts us to search both for new compounds and for their new potential application. The aim of this study was to examine the influence of ionic liquids (ILs) on the cellulose product, paper. In the studies, commercially available 3-alkyl-1-methylimidazolium tetrafluoroborates and prepared 3-alkoxymethyl-1-methylimidazolium tetrafluoroborates and 3-alkoxymethyl-1-methylimidazolium bis(trifluoromethanesulfonyl)imides were used. Obtained salts with bis(trifluoromethanesulfonyl)imide anion are new compounds. ILs were found to impregnate paper, affecting its strength and other physical parameters. Various properties of paper were distinctly altered after treatment with ILs of varying anions. In general, IL-treated paper had decreased strength, which resulted from weakening of cellulose hydrogen bonds. On the other hand, paper wettability improved. Paper treated with 1-methyl-3octyloxymethylimidazolium tetrafluoroborate proved to be fully resistant to activity of moulds and fungi, inducing the blue discoloration of the paper.