<p>Flocculation is one of the steps to get clean water. Grafted flocculant was successfully synthesized by combining the benefits of synthetic polymers (polyacrylamide) and natural polymers (cassava starch). This synthesis used “grafting to” method and passed through two stages, i.e. (i) the synthesis of non-terminated polyacrylamide (nt-PAM) and followed by (ii) grafting of non-terminated polyacrylamide (nt-PAM) on the cassava starch. The obtained flocculants were analyzed their molecular structure to determine the success of grafting. Fourier Transform Infra-Red (FTIR) spectra were verifying that polyacrylamide can be attached in the starch molecules. Both neat starch and modified starch were studied as a backbone. The molecular weight of the flocculant is increasing as the increase of acrylamide concentration and polymerization time. The effectiveness of flocculation is relating with the molecular weight. However, the longer chains of attached polyacrylamide show better performance during flocculation than that of shorter chains although the molecular weight was same. The best performance was showed for the flocculant that using: (i) modified starch of cassava as a backbone, (ii) acrylamide concentration of 0.02 M and (iii) polymerization time of 90 minutes. As monitored, it could reduce the turbidity of artificial wastewater about 87,81 %</p>