Copper trimesates with isomorphously substituted molybdenum and zinc, which are isostructures of copper benzene-1,3,5-tricarboxylate (abbreviated as CuBTC), were mechanochemically synthesized using Zn2+, Mo2+, and Cu2+ acetates as inorganic precursors at room temperature. Isomorphous substitution of molybdenum in the CuBTC framework was successfully traced by refining the unit cell parameters based on the Mo and Zn contents. X-ray photoelectron spectroscopy was used to determine that the oxidation state of molybdenum in copper trimesate was +6 (instead of +2, which is expected based on the Mo precursor). In situ Fourier transform infrared (FT-IR) spectra of CO adsorption at 100 K were used to quantitatively estimate the coordinatively unsaturated metal sites in trimetallic copper trimesate. The oxidation performance of trimetallic copper trimesate was studied through epoxidation of cis-cyclooctene with tert-butylhydrogenperoxide as an oxidant. Trimetallic copper trimesate is highly efficient for catalytic oxidation with a high selectivity to cyclooctene oxide and can be recycled without a significant activity loss.