Partial hydrogenation of alkynes to alkenes constitutes a very important process in organic chemistry. Lindlar catalyst (with quinoline) and P-2 nickel (with ethylenediamine) are well known catalysts as a selective partial hydrogenation of alkynes. Especially, Lindlar catalyst is even now widely used in industry and laboratory, while Lindlar catalyst is poisoned by lead which is highly toxic and environmentally-unfriendly. In general, nitrogen-containing bases are often utilized as catalyst poisons of Pd such as Pd/C(en) catalyst. Therefore, polyethyleneimine possessing numerous nitrogen-containing base within the molecule would be expected to reduce the catalyst activity of Pd catalyst. We developed a novel and chemoselective hydrogenation catalyst, Pd(0)-PEI complex. Consequently Pd(0)-PEI is applicable to the partial hydrogenation of di-substituted alkynes to cis-alkenes. It should be noted that Pd(0)-PEI catalyst efficiently catalyzes the partial hydrogenation of wide range of mono-substituted(terminal) alkynes, which is easily hydrogenated to alkanes under the Lindlar catalyst catalyzed hydrogenation conditions.