Selected ancient Greek bronze coins held in the Coin Collection of the Kunsthistorisches Museum Vienna (KHM) were studied concerning their preservation and conservation. The coins had been minted during the Roman Imperial time (50 to 280 AD) using alloys with high lead and/or tin contents. Today a number of these highly leaded bronze coins, altogether different singular pieces, show progressive whitish corrosion in spots or well-defined areas on their surfaces. Different analytical techniques were used for the documentation and study of the different states of corrosion, the corrosion phases developing in the whitish parts as well as the cause of the specific corrosion phenomena.