Onggok, solid waste of tapioca still contains high carbohydrate. This component can be converted to liquid sugar (glucose and fructose). Hydrolysis process convert carbohydrate become glucose syrup while isomerization process would change those glucose become fructose syrup. This study aims to produce fructose from Onggok with isomerization by Mg/Al hydrotalcite catalyst and compare the productivity 500ml Onggok substrate (10.32 percent DS) was hydrolyzed become glucose in liquefaction and saccharification process. Liquefaction took placed in 95 degree C, pH 6.5, for 1 hour, by adding 0.067 percent (v/v) α-amylase while the saccharification was start by adding 0.067 percent (v/v) glucoamylase at 60 degree C, pH 5, for 1 hour. Isomerization with Mg/Al hydrotalcite took placed in 50 ml hydrolysate sugar, 1 percent (b/v) catalyst, and 100 degree C while process with glucose isomerase was at 100 ml substrate, 60 degree C, pH 8.2, and same catalyst ratio (1 percent). Isomerization process for each catalyst would be hold in 3, 5, and 7 hours. The best result of isomerization productivity was 39.29 g/L. h for process with Mg/Al hydrotalcite catalyst, while isomerization yield was 6.18 percent for process with glucose isomerization enzyme.