This paper discusses smelting technology at the Sungai Batu SB2A iron smelting site in the Bujang Valley, Kedah, Malaysia, which was dated to the first to fifth centuries CE through radiocarbon, AMS-dating and OSL techniques. Findings at the site include iron slag, a fragment of tuyere, iron ore, laterite, brick, segments of a furnace wall, beads, ceramics, lithics and iron artifacts. This paper presents dating evidence, and discusses the results of XRF, XRD, SEM-EDX and metallurgy studies of the iron artifacts, slag and ore. The analyses suggest that iron smelting activities were carried out by employing the bloomery technique, using temperatures of 1150-1200°C, probably without using catalyst material or flux, and that Bukit Tupah is the resource area for haematite used at the site. The archaeological data suggest that prehistoric societies at Sungai Batu employed direct smelting techniques (Naizatul Akma Mokhtar et al. 2011), with the construction of a clay furnace and the use of tuyeres and bellows. The Bujang Valley appears to have functioned not only as a center of exchange for foreign commodities, but also of local industry. The ancient glory of the Bujang Valley as an entrepôt was not only due to its advantageous location, but also to the commodities that it was producing.