Abstract: During the production of palm sugar, the palm sap (Arenga pinnata) is heated up to 150 ° C. Besides the hydrolysis of carbohydrate to generate reducing sugars and degradation of amino acid, many physico-chemical changes produced at all these temperatures, having a significant impact on the overall quality of palm sugar. In this study, changes in physico-chemical properties of the palm sap due to heat processing were investigated. Analysis of colour, soluble solid, pH, temperature, sugar and amino acid concentration was determinant. The results showed clearly that the heating process at these high temperatures was necessary to create an environment which was rich in essential precursors for subsequent reactions such as Maillard reaction. Chemical compounds that showed drastic changes in concentration were polar side chain amino acids especially glutamine, asparagine and arginine as well as sucrose and pH value. Other quality characteristics of palm sugar based on colour and soluble solids ( ° Brix) shared an increase in concentration as a function of time.