The performance of supported palladium catalysts that had been modified with triphenyl phosphine, diphenyl sulfide and triphenyl amine was compared to unmodified Pd/TiO2 catalysts. It was found that the selectivity was superior to the unmodified catalysts with or without the use of carbon monoxide as a modifier. Ethylene selectivities in excess of 70 % at conversion levels greater than 80% were observed on the modified catalysts under conditions of excess hydrogen which compares extremely well with other catalysts found in the literature. The modifier was found to significantly reduce the number of high energy sites on the surface on the palladium, thereby significantly hindering ethylene hydrogenation but not affecting acetylene hydrogenation. The simple preparation of these catalysts together with the simplicity added by not having to use carbon monoxide or limited hydrogen promises a viable alternative strategy for commercial catalysis.