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The date palm is one of the oldest crops grown especially in arid and semi-arid bioclimatic zones of the Arabian Peninsula, North Africa and in the Middle East. The number of date palms in the world has been estimated by 100000 million trees; with 2 603 500 date palm trees in an area of 22 680 ha in Tunisia tree. The global palm date waste production is approximately 2 million t/year. The lif is the by-product of the palm date tree. Thus, it could be considered as an available lignocellulose feedstock. For this reason, the aim of this work was to produce bioethanol 2G as renewable source of energy from both young and old lif of date palm, Phoenix dactylifera L. Therefore, to reach this purpose, the first step was to optimize the thermochemical pretreatment while studying the effect of the two main factors: temperature and acid concentration, in order to have the maximum yield of D-glucose. The second step was to explore enzymatic hydrolysis, and the last one was the fermentation process. This research proves that the most adequate conditions for pretreatment of both wastes date palm are 220 degrees C in hydrothermal conditions (H2SO4 at 0 M). Indeed, these operating conditions allow to obtain reducing sugars concentrations about 2.39 +/- 1.09 g/dm(3) for young lif and 1.98 +/- 0.12g/dm(3) for old lif, and D-glucose concentrations about 0.11 +/- 0.13g/dm(3) for young fibers and 0.093 +/- 0.016 g/dm(3) for old fibers. After enzymatic hydrolysis, the hydrolysates containing D-glucose were fermented by Pachysolen tannophilus to ethanol, reaching 3.24 +/- 0.81 g/dm(3) for young lif and 4.55 +/- 1.04 g/dm(3) for old lif, respectively.