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Pectinesterase (E C 3.1.1.11) was extracted from papaya (Carica papaya L.) tissue and purified 4,48 fold by fractionated ammonium sulphate precipitation, dialysis and chromatography on DEAE-celulose and Sephadex G-100. Extraction conditions of enzyme were studied and their properties characterized. The increase on the activity of pectinesterase was practically followed by increase on the content of soluble pectin, during ripening. The molecular weight of the enzyme eluted in one peak of activity was 53.000 daltons. The pectinesterase has its maximum activity at pH 8,0 and at 0,2 M of NaCl. Optimum temperature for the enzyme assay was 60°C. The enzymatic reaction was linear with the time and protein concentration. With citric pectin as substrate, pectinesterase had a K_m of 0,012% and was inhibited competitively by polygalacturonic acid with a K_i of 0,007%. Papaya pectinesterase was inhibited by sucrose, glucose and glicerol.