A catalyst system comprising a combination of: 1) one or more catalyst compounds having at least one nitrogen linkage and at least one oxygen linkage to a transition metal; 2) a support comprising an organosilica material, which is a mesoporous organosilica material; and 3) an optional activator. Useful catalysts include ONNO-type transition metal catalysts, ONYO-Type transition metal catalysts, and/or oxadiazole transition metal catalysts. The organosilica material is a polymer of at least one monomer of Formula [z′OZ2 SiCH2]3(l), where Z1 represents a hydrogen atom, a C1-C4alkyl group, or a bond to a silicon atom of another monomer and Z2 represents a hydroxyl group, a C1-C4alkoxy group, a C1-C6alkyl group, or an oxygen atom bonded to a silicon atom of another monomer. This invention further relates to processes to polymerize olefins comprising contacting one or more olefins with the above catalyst system.