Carboxymethyl chitosan (CMC) was evaluated for its use in the synthesis and stabilization of catalytic nanoparticles for the first time. Many studies have reported on the ability of chitosan to bind with metal ions and support metal nanoparticles. CMC has a higher reported chelation capacity than chitosan, which has potential implications for improved catalyst formation and immobilization. Platinum, gold, and silver nanoparticles were synthesized in both chitosan and CMC. Particle size, morphology, and aggregation were examined using transmission electron microscopy (TEM). Complexation of nanoparticles was studied through Fourier transform infrared spectroscopy (FTIR). Similar nanoparticle size distributions were observed in the two polymers; however, CMC was observed to have higher rates of aggregation. This indicates that the carboxymethyl groups did not change nanoparticle formation; however, poor cross-linking and a limited anchoring ability of CMC led to the inability to immobilize the catalyst materials effectively.