Ostracod (Crustacea) fossils could be determined only by observation of the carapace and for this they have to be extracted from the rocks. Generally, in Late Palaeozoic rocks, these microfossils are preserved in hard limestones. The most common method of their extraction is hot acetolysis. We test here two other methods for ostracod extraction from the Guadalupian-Lopingian (Late Permian) Ali-Bashi section in the Northwest of Iran. The samples were prepared with cold 10% formic acid (CH₂O₂) and 15% acetic acid (CH₃COOH). The CH₂O₂ protocol was productive with well-preserved ostracods, allowed us to determine ten taxa as Bairdia deducta deducta (Zalanyi, 1974), Bairdia hungarica Zalanyi, 1974, Bairdia sp., Fabalicypris parva, Wang 1978, Fabalicypris sp. 1, Fabalicypris sp. 2, Hollinella (Hollinella) herrickana (Girty, 1909), Hollinella sp., Sargentina transita (Kozur, 1985) and Silenites sp. Amongst these assemblages, Hollinella (Hollinella) herrickana (Girty, 1909) and Sargentina transita (Kozur, 1985) were obtained exclusively through the diluted CH₂O₂ protocol from the hard dolomitized limestones, while the other hot and cold procedures were unsuccessful.

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