Drying, calcination, prereduction, and smelting are the main steps in conventional crude ferronickel production. Industrially, these steps are conducted using the rotary kiln-electric arc furnace (RKEF) process. In this paper, calcination characteristics of Sivrihisar laterite ores from the Central Anatolia region are investigated. The extent of elimination of chemically bound water and other volatiles was studied by experiments conducted at various temperatures in the 250-800 degrees C range. Phase changes were examined using X-ray diffractometry. For the particle size used in the study, 300 degrees C was determined to be almost sufficient for complete transformation of goethite to haematite, and 700 degrees C was required for effective elimination of all volatiles in the ore.