The conversion of methyl oleate by cross-metathesis with ethylene using readily accessible supported group VI oxo species was addressed. TON up to 500 and 5000 were achieved using bisgrafted tungsten- and molybdenum based systems, respectively (≡SiO)2M(═O)R2(M = W, R = CH2SiMe3, M = Mo, R = CH2CMe3). In the case of molybdenum, these results are comparable to those obtained by Mo-based systems in homogeneous catalysis. Optimization studies showed that ethylene pressure plays a major role in these systems, with inhibition at high pressure resulting from degenerated metathesis involving ethylene and α-olefins.