To overcome the problems of conventional absorption working fluids, the novel hydrofluoroolefins (HFOs) and ionic liquid (IL) were analyzed. The refrigerants were 2,3,3,3-tetrafluoropropylene (R1234yf) and trans-1,3,3,3tetrafluoropropene (R1234ze(E)), and the absorbent was 1hexyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide ([hmim][Tf2N]). The property models of HFO/IL and the thermodynamic models of absorption cycles were built with verified accuracy. Analyses show that the coefficient of performance (COP) of R1234yf/[hmim][Tf2N] is up to 0.414, while that of R1234ze(E)/[hmim][Tf2N] is up to 0.498. The better performance of R1234ze(E)/[hmirn][Tf2N] is contributed by its higher solubility and lower saturation pressure. The compression-assisted cycle not only extends the operation range but also improves the COP for both HFO/IL pairs. The minimum generation and evaporation temperatures are reduced by 17 and 11 degrees C under a compression ratio of 1.5. The COPs of HFO/IL are lower than those of H2O/LiBr and NH3/H2O. More HFO/IL mixtures need to be explored for further performance improvement.