Ethylene oligomerization

An ethylene oligomerization process consisting essentially of:

• oligomerizing ethylene under oligomerization conditions with an oligomerization catalyst system produced by the process consisting essentially of contacting an organonickel compound, an aromatic acid compound, a phosphine compound;
• wherein the nickel component is in the zero valence state or can undergo reduction to the zero valence state, and the organic component is an unsaturated organic group;
• and
• wherein said aromatic acid compound has the following formula ##STR2## wherein each R is independently selected from the group consisting of hydrogen, and hydroxyl (-OH), provided that, at least one R is not hydrogen;
• and
• wherein said phosphine compound has the formula PR.sub.3, wherein each R is independently selected from the group consisting of hydrogen and hydrocarbyl radicals, provided that said hydrocarbyl radical has 1 to about 20 carbon atoms and that any alkenyl substitution be at least 3 carbon atoms removed from the phosphorous atom and at least one R is not a hydrogen;