Thin films of the tetragonal rutile-type SnO2 phase have been deposited by both atomic layer deposition (ALD) and chemical vapour deposition (CVD) using the SnI4–O2 precursor combination. Depositions were carried out in the temperature region of 350–750 °C on α-Al2O3(0 1 2) substrates. In both cases the films were found to grow epitaxially with the in-plane orientation relationships [0 1 0]SnO2 || [1 0 0]α-Al2O3 and [1 0 1¯]SnO2 || [1¯ 2¯ 1]α-Al2O3. Films grown by ALD were found to be close to perfectly single crystalline, contained a low density of defects and were almost atomically smooth. The CVD films were found to have a much rougher film morphology, and exhibited both grain boundaries and twin formation.