Pool nucleate boiling characteristics of R-114, distilled water (H2O) and R-134a on plain and rib-roughened tubes (rib pitch 39.4 mm, rib height 4 mm, rib width 15 mm. number of element 8, rib angle 30-90-degrees) geometries were extensively studied. Boiling data for both increasing/decreasing heat flux modes as well as the influences of heat flux level on heat transfer coefficient were presented and discussed. Enhancement performance ratios were calculated and compared for three different refrigerants and different tube geometries. Furthermore, it is found that smooth tube data agreed quite well with those of previous results.