Bulk chemical compositions and oxygen isotopic compositions were analyzed for 48 stony cosmic spherules (melted micrometeorites) collected from the Antarctic ice sheet using electron- and ion-microprobes. No clear correlation was found between their isotopic compositions and textures. The oxygen isotopic compositions showed an extremely wide range from -28 parts per thousand to +93 parts per thousand in delta(18)O and from -2,1 parts per thousand to +13 parts per thousand in Delta(17)O. In delta(18)O-delta(17)O space, most samples (38 out of 48) plot close to the terrestrial fractionation line, but 7 samples plot along the carbonaceous chondrite anhydrous mineral (CCAM) line. Three samples plot well above the terrestrial fractionation line. One of these has a Delta(17)O of +13 parts per thousand, the largest value ever found in solar system materials. One possible precursor for this spherule could be O-16-poor planetary material that is still unknown as a meteorite. The majority of the remaining spherules are thought to be related to carbonaceous chondrites. Copyright (c) 2005 Elsevier Ltd.