The nonlinear optical (NLO) properties of covalently linked Graphene-(Sn, OH) porphyrin composite materials were investigated using Z-scan technique at 532 nm with picosecond laser pulses. We have observed enhanced figure of merit values for composites in comparison with individual graphene, copper and zinc porphyrin. The enhanced figure of merit values for graphene-porphyrin composite material should be attributed to two-photon absorption and excited state absorption. We also observed different behavior, reverse saturable absorption to saturable absorption and back to reverse saturable absorption in composite molecules leading to better ultrafast nonlinear optical switching applications. © 2011 American Institute of Physics.