Biodiesel can be obtained by esterification reactions of free fatty acids with enzymatic catalysts (lipases). In this study, the immobilized Candida antarctica lipase was employed in enzymatic esterifications of oleic acid with aliphatic alcohols (methanol, ethanol, n-propanol, n-butanol). Some features that influence the enzymatic esterification reaction, such as amount of biocatalysts, reaction time, hydration level and biocatalyst turnover were evaluated. The products were determined by GC-FID and H-1 NMR analyses and these analytical methods were compared. The enzymatic catalyst (C. antarctica lipase) was efficient providing high yields of biodiesel (above 90 %) in less than 24 h to ethanol, n-propanol and n-butanol, whereas for methanol, the enzyme was inactive after ten cycles of reaction. Two new quantitative easy methods were also developed to quantify esters produced by H-1 NMR based on the alpha-CH2 protons of oleic acid and esters. The quantification method used in the enzymatic reactions by H-1 NMR showed effective with small differences in comparison with GC-FID analyses.