The miscibility behavior of N-butylpyridinium nitrate/N-octylpyridinium blends with different compositions was studied using the inverse gas chromatography (IGC) technique. Twenty-one solvents, including alkanes, cycloalkane, aromatic hydrocarbons, alcohols, ethyl ether, acetone, and esters, with different chemical properties were studied to evaluate the interaction between N-alkylpyridinium nitrates and solvents. The interaction parameters of different ionic liquids [ILs] have been calculated. Results were consistent with the activity coefficients at infinite dilution and weight fraction activity coefficient. In addition, the miscibility term Delta H-1(S) was significantly different in each obtained IL blend. The solubility parameters of N-butylpyridinium nitrate/N-octylpyridinium blends were derived using the calculation delta(2)(1)/(RT) - chi(infinity)(12)/V-1 versus delta(1) of probes. The altered values of the solubility parameters were consistent with those of the studied ILs based on the methylimidazolium cation.