A self-metathesis process for the production of unsaturated dicarboxylic acids and/or unsaturated dicarboxylic diesters, wherein unsaturated carboxylic acids having from 14 to 24 carbon atoms and/or esters of such unsaturated carboxylic acids are reacted in the presence of at least one catalyst selected from the group consisting of: [1,3-bis(2,6-diisopropylphenyl)-2-imidazolidinylidene]dichloro [2-(1-methylacetoxy) phenyl]methyleneruthenium; [1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro [2-(1-methylacetoxy) phenyl]methyleneruthenium; [1,3-bis(2,6-diisopropylphenyl)-2-imidazolidinylidene]dichloro[[2-(2-oxopropoxy) phenyl]methylene]ruthenium; [1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro[[2-(2-oxopropoxy) phenyl]methylene]ruthenium; ([1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinyliden]dichloro[(2-isopropoxy)(5-trifluoracetamido)benzyliden]]ruthenium); ([1,3-bis(2,6-diisopropylphenyl)-2-imidazolidinyliden]dichloro[(2-isopropoxy)(5-trifluoracetamido)benzyliden]]ruthenium); ([1,3-bis(2,6-diisopropylphenyl)-2-imidazolidinyliden]dichloro[(2-isopropoxy)(5-isobutoxyacetamido)benzyliden]]ruthenium); ([1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinyliden]dichloro[(2-isopropoxy)(5-isobutoxyacetamido)benzyliden]]ruthenium); ([1,3-bis(2,6-diisopropylphenyl)-2-imidazolidinyliden]dichloro[(2-isopropoxy)(5-ethylesteracetamido)benzyliden]]ruthenium); and ((1,3-bis(2,6-diisopropylphenyl)-imidazolidin-2-yliden)((2-ethyl-3-oxo-3,4,-dihydr-2H-benzo[b][1,4]oxazin-8-yl)methylene)ruthenium chlorid); and the process additionally comprises the presence of a catalyst enhancer compound selected from boron trifluoride, boron trichloride, boron triiodide, boron tribromide, or titanium compounds having the general formula Ti. 4 wherein each Q independently represents hydrogen, a C1 to C10 alkoxy group, a halide, a C12 to C18 fatty alcohol or a C6 to C18 fatty acid. [1,3-bis(2,6-diisopropylphenyl)-2-imidazolidinylidene]dichloro [2-(1-methylacetoxy) phenyl]methyleneruthenium; [1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro [2-(1-methylacetoxy) phenyl]methyleneruthenium; [1,3-bis(2,6-diisopropylphenyl)-2-imidazolidinylidene]dichloro[[2-(2-oxopropoxy) phenyl]methylene]ruthenium; [1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinylidene]dichloro[[2-(2-oxopropoxy) phenyl]methylene]ruthenium; ([1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinyliden]dichloro[(2-isopropoxy)(5-trifluoracetamido)benzyliden]]ruthenium); ([1,3-bis(2,6-diisopropylphenyl)-2-imidazolidinyliden]dichloro[(2-isopropoxy)(5-trifluoracetamido)benzyliden]]ruthenium); ([1,3-bis(2,6-diisopropylphenyl)-2-imidazolidinyliden]dichloro[(2-isopropoxy)(5-isobutoxyacetamido)benzyliden]]ruthenium); ([1,3-bis(2,4,6-trimethylphenyl)-2-imidazolidinyliden]dichloro[(2-isopropoxy)(5-isobutoxyacetamido)benzyliden]]ruthenium); ([1,3-bis(2,6-diisopropylphenyl)-2-imidazolidinyliden]dichloro[(2-isopropoxy)(5-ethylesteracetamido)benzyliden]]ruthenium); and ((1,3-bis(2,6-diisopropylphenyl)-imidazolidin-2-yliden)((2-ethyl-3-oxo-3,4,-dihydr-2H-benzo[b][1,4]oxazin-8-yl)methylene)ruthenium chlorid); and the process additionally comprises the presence of a catalyst enhancer compound selected from boron trifluoride, boron trichloride, boron triiodide, boron tribromide, or titanium compounds having the general formula Ti. 4 wherein each Q independently represents hydrogen, a C1 to C10 alkoxy group, a halide, a C12 to C18 fatty alcohol or a C6 to C18 fatty acid.