Polymerization of the [(eta(5)-C5H4(CH2)(8)CH=CH2)Mo(CO)(3)](2) complex by acyclic diene metathesis polymerization (ADMET) is reported. The polymerization reactions were performed using Schrock's catalyst, which resulted in formation of a polydisperse oligomer (M-n = 2300 and M-w/M-n = 4.3) with Mo-Mo bonds in the oligomer chain. Under dilute solvent conditions, the reaction wits shown to favor file formation of the ring-closing metathesis (RCM) product. The ADMET oligomer was photochemically degradable, and irradiation with lambda > 520 nm light in CCl4 resulted in cleavage of the oligomer backbone and formation of the metal chloride complex [mu-C5H4(CH2)(8)CH=CH(CH2)(8)C5H4{Mo(CO)(3)Cl}(2)]. The RCM product was also irradiated and the photochemical product is identical to that formed by irradiation of the oligomer. Copolymerization of [(eta(5)-C5H4(CH2)(8)CH=CH2)Mo(CO)(3)](2) with 1,9-decadiene using Grubbs' second-generation catalyst resulted in a higher molecular weight oligomer (M-n = 3400, M-w/M-n = 3.9).