Descriptions, illustrations, discussion and an identification key are presented for six saxicolous and terricolous species of the lichen genus Bacidia De Not. occurring in temperate Australia and Tasmania. Three species are described as new to science: B. lithophila Kantvilas from northern Tasmania, characterized by having only brown apothecial pigments and 3–5-septate, acicular ascospores, 23–35×1·5–2·0 µm; B. littoralis Kantvilas from Tasmania, South Australia (Kangaroo Island) and New South Wales, characterized by green and brown apothecial pigments and acicular, 3–7-septate ascospores, 24–48×2·0–3·5 µm; and B. maccarthyi Kantvilas from New South Wales, with pruinose apothecia and long, filiform, 17–25-septate ascospores, 65–115×2·5–4·0 µm. Three further species are reported for the region for the first time: B. bagliettoana (A. Massal. & de Not.) Jatta (Tasmania), B. curvispora Coppins & Fryday (Tasmania) and B. scopulicola (Nyl.) A. L. Sm. (Tasmania, Victoria).