Disclosed is a process for hydroformylation of α-olefin wherein said α-olefin is reached with carbon monoxide or carbon monoxide and hydrogen and/or a reducing agent in presence of a catalyst complex based on a rhodium precursor and a ligand mixture comprising at least 1% by weight of trphenylphosphine and at least 5% by weight of diphenylcyclohexylphosphine, tris-(o-tolyl)phosphine, tris-(p-tolyl)phosphine or (2-methyl-phenyl)diphenylphospine.