Stable solutions of Co carbonyl are prepared by causing a suspension of a Co compound to react in a neutral organic liquid with CO at above 140° and at superatmospheric pressure. Yields of 80% minimum in 2 hr. are obtained batchwise in a shaking bomb. In an example, 14 gm. CoCO3 precipitated on 6 gm. diatomaceous earth and suspended in 200 cc. diisopropyl ether are charged to a shaking bomb. The apparatus is flushed with CO and then charged with a 50-50 mixture of CO and H2 at 2,600 p. s. i. With shaking, the bomb is heated to 160° in 30 min. and then held for 2 hr. The apparatus is cooled to 20° . After venting, a dark brown, clear liquid product is obtained which assays 9.8% Co carbonyl. Other Co salts can be used and a variety of organic solvents is suggested.