Abstract: Studies describing the ethanol bio-production from ricotta cheese whey still are few and this limits the development of an industrial bioprocess. The aim of this study was to compare the ethanol productivity by several strains of the yeast Kluyveromyces, from non-sterilized and sterilized ricotta cheese whey, named respectively in this study like Non Heat Treated (NHT) and Heat Treated (HT), in order to select the most suitable strain for lactose conversion of this whey into ethanol and check the possible interference of the thermal treatment from ricotta cheese whey in the ethanol productivity. The yeasts K. marxianus ATCC 16045, K. marxianus ATCC 46537, K. marxianus ATCC 12424, K. marxianus CBS 6556 and K. lactis ATCC 24176 were used in this study. The yeast K. marxianus ATCC 16045, K. marxianus ATCC 46537 and K. marxianus ATCC 12424 showed the highest efficiency of ethanol production (η) in HT ricotta cheese whey. The maximal growth rate (μmax) and cell mass productivity (QX) values were found to be highest by K. marxianus ATCC 12424 from HT ricotta cheese whey, whereas the ethanol productivity (QP), yield coefficient for ethanol on cell mass (YP/X) and efficiency of ethanol production were the highest by K. marxianus ATCC 46537 from HT ricotta cheese whey. The yeast strains K. marxianus CBS 6556 and K. lactis ATCC 24176 from both NHT and HT ricotta cheese whey showed the lowest values for the growth kinetics determinants and conversion rate parameters for the ethanol production. In the evaluated culture conditions, the yeast K. marxianus ATCC 46537 from HT ricotta cheese whey showed the best results for ethanol production.