The effect of temperature and pH on the cross-linking reaction of tapioca starch were studied. It was found that the temperatures at 45 ± 2.0ºC and 50 ± 2.0ºC and pH between 10.0 to 11.5 did not significantly affect Brabender viscosity at 95° C of the starch paste. Therefore, the cross-linking of aqueous starch suspension at 45 ± 2.0° C and pH 10.0 was carried out to examine the effect of sodium trimetaphosphate concentration and reaction time on the degree of cross-linking. Increasing sodium trimetaphosphate concentration and reaction time increased the degree of cross-1 inking which can be determined by measuring the viscosity stability of the starch paste during heating cycle. It was found that as the degree of cross-linking increased, the viscosity of the starch paste became progressively more stable and pasting temperature increased. The maximum viscosity of the starch paste and its stability were achieved by the cross-linking using 1.4% sodium trimetaphosphate for 16 hours. The paste properties of the cross-linked tapioca starch were also investigated. It was found that as the extent of cross-linking progressed, the residual phosphate and Brabender viscosity at 50° C for 30 minutes in the pH range of 3.0 to 5.0 increased but the swelling power decreased. It was also observed that Brabender viscosity pattern of the cross-linked tapioca starch paste at 8% concentration was more similar to that of mung bean starch. In the study of using the cross-linked tapioca starch as stabilizer in tomato ketchup, the results showed that the starch modified with 2% sodium trimetaphosphate at 1% used level provided the best quality in both viscosity and organoleptic properties and could maintain these qualities at room temperature for at least 6 months. For beanthread application, the substitution of mung bean starch with 50% cross-linked starch modified with 2% sodium trimetaphosphate showed no difference in organoleptic evaluation com pared with grade A beanthread (the ratio of mung bean starch : tapioca starch is 90:10).