Preparation of calsium oxide (CaO) from cockle shell (Anaciara Granosa) through decomposition at various temperature i.e. 600°, 700°, 8000, 900°. 1000°, 1100°C has been carried out. Characterization of CaO from decomposition was used XRD. The results, of XRD showed that diffraction pattem of CaO at 900°C similar with diffraction of CaO from JCPDS file Standard the 20 value 34,2°, 37,3°,…