Kephala and Phournoi, on the island of Seriphos, add to a growing number of EBA metal production sites identified in the south-central Aegean. Analytical examination of samples from the two sites addressed the technological parameters of the copper smelting process, indicating the use of mixed oxidic and sulphidic copper–iron ores to produce unalloyed copper with minute copper sulphide inclusions. A preliminary geological reconnaissance of the island identified several small copper mineralizations, one of them close to the site of Kephala. Nevertheless, the ore sources used remain unclear. Comparisons are made with other contemporaneous neighbouring smelting sites.