Abstract: A catalyst for trimerization of ethylene is disclosed which comprises (a) a chromium complex having a neutral multidentate ligand having a tripod structure, represented by the formula, ACrJnQ3-n wherein A is a neutral multidentate ligand having a tripod structure, J is a carbonyl ligand or halogen, n is an integer of 0-3, and Q is at least one member selected from hydrogen, a C1-C10 hydrocarbon group, a C1-C10 carboxylate group, a C3-C10 diketonato group, an amide group, an imide group, an C1-C10 alkoxide group, a C1-C10 thioalkoxide group, an C6-C15 arene ligand, an C2-C10 alkene ligand, an C2-C15 alkyne ligand, an amine ligand, an imine ligand, an isonitrile ligand, a phosphine ligand, a phosphine oxide ligand, a phosphite ligand, an ether ligand, a sulfide ligand, a sulfone ligand and a sulfoxide ligand, and (b) a metal alkyl compound.