Let f : A → B be a ring homomorphism of the commutative rings A and B with identities. Let J be an ideal of B. The amalgamation of A with B along J with respect to f is a subring of A × B given byIn this paper, we investigate the comaximal ideal graph and the comaximal graph of the amalgamated algebra A f J. In particular, we determine the Jacobson radical of A f J, characterize the diameter of the comaximal ideal graph of A f J, and investigate the clique number as well as the chromatic number of this graph.