Four model caramelisation products (CPs) have been prepared by heating different Saccharides solutions (glucose, fructose, lactose and xylose) at 100°C for 3 hours at different pH( 2.5, 4, 7 and 10). Both Browning and intermediate thermal degradation products {the caramelisation products} were studied using ultraviolet /visible spectrophotometer. Generally, the results showed that CPs increased with increasing heating time, and the formation rate depends upon the type of Saccharides and pH value. The reducing power of the four distinct CPs was defined, also. Among all the Saccharides tested, fructose CPs exhibited the highest reducing power values in alkaline solutions. Finally, the concentration changes of Saccharides during heating were quantitatively defined by using high performance liquid chromatography HPLC.