This paper reports the results of studies related to air oxidations of (-)-alpha-pinene, catalysed by plain Co(II) salts without a sacrificial co-oxidant. CoCl2, CoBr2, Co(OAc)(2) and Co(NO3)(2)-catalysed air oxidations were performed at 60, 80 or 100degreesC. The favourable effect of a small amount of tert-butyl hydroperoxide or glacial acetic acid on these air oxidations is discussed. (C) 2002 Elsevier Science B.V. All rights reserved.