This paper aims to assess the pozzolanic characteristics of the volcanic ash obtained from Jebal Tagabo (Tagabo Mountains) in western Sudan (North Darfur State) as potential Supplementary Cementitious Materials for use in blended cement and concrete. Four natural Pozzolanic materials samples have been obtained; the first is volcanic ash from the Garma region (TG1VA), the second from the Mabo region (TG2VA), the third from the Mawo region (TG3VA) and the last from the Daim Sanosi region (TG4VA). This study has investigated the chemical and physical characteristics of the samples and their pozzolanic activities with Ordinary Portland cement (OPC) at different substitution levels of cement by weights, which are 10, 20, 30, 40, and 50%. And the results of chemical analysis show that all samples can be classified as Class N according to the American standard ASTM C618. The strength activity indices of the four samples at 20% level were found to be 75, 84, 89, and 83% respectively. These results indicate that the Jebal Tagabo Pozzolans are potential supplementary cementitious materials for use in blended cement.