In this paper, we present a new protocol to synthesize dihydrodicyclopentadienes (DHDCP), via mono hydrogenation of dicyclopentadiene. With the use of Pd-nanoparticles as catalysts the products are formed highly selective under mild conditions. The ratio between the DHDCP and the tetrahydrodicyclopentadiene (THDCP) can be shifted by variation of the hydrogen pressure from 7:1 to 1:8, with high conversions of over 85 %. The product DHDCP is an essential building block in co-polymerizations. Also we show an easy recycling concept for the nanocatalyst by phase separation. With simple filtration the solid products DHDCP and THDCP can be isolated and the liquid catalyst phase can directly be reused. Over all recycling runs a steady high conversion of about 75 % was observed. Palladium nanoparticles in solution are an efficient catalyst for the selective monohydrogenation of dicyclopentadiene to the two dihydrodicyclopentadienes. High selectivities up to 95 % could be obtained after one hour under mild reaction conditions of 60 A degrees C and 5 bar hydrogen pressure. Besides we could show an easy catalyst recycling concept by the liquid-solid two-phase technique.