A radioactivity mapping program was developed to support the decision making in case of a radiological emergency event. Geostatistics and kriging methods were used in the program to make a more accurate radioactivity map for the polluted area. Two variogram models, i.e., linear and exponential models, were tested, and the exponential variogram model showed a better performance when compared with the linear interpolation for estimating unobserved data for radioactivity.