Transition metal complexes and nanoparticles have versatile features to act as catalysts and in the recent years, are therefore increasingly being applied in organic transformations. Hydroformylation and hydrogenation are such examples and industrially performed by transition metal based catalysts. Hydroformylation is an elegant method to synthesized aldehydes in a single step from alkenes using syngas whereas hydrogenation is powerful tool in a wide range of organic synthesis. Both reactions have numerous applications in the petrochemical, pharmaceutical, fine chemicals and food industries. However, there is requirement to develop catalyst system having a proper balance between catalytic activity and selectivity and can be separated from reaction mixture. In this book, the attention is given to synthesize catalyst systems utilizing various transition metals (Co, Rh, Ru and Pd) and their catalytic studies in hydroformylation and hydrogenation. The designing of modified phosphorus ligands, conversion of higher olefins in aqueous biphasic system and different approaches to recovery and reuse catalyst are describe with problems associate with hydroformylation and hydrogenation.