An atomic layer deposition (ALD) process was developed for an important thermoelectric material Bi2Se3 utilizing dechlorosilylation reactions between BiCl3 and (Et3Si)2Se precursors. The applicability of this alkylsilyl selenide precursor was confirmed, as reactions with BiCl3 produced good quality thin films with low impurity contents. Saturation of the growth rate with regards to the pulse lengths of both precursors indicated that the Bi2Se3 process had characteristic ALD properties. Also, the film thickness corresponded linearly with increasing number of deposition cycles. No ALD window was discovered and the growth rates decreased significantly with increasing temperatures, similarly to other ALD processes utilizing alkylsilyl chalcogenide precursors. Nevertheless, high growth rates of 1.6 Å per cycle occurred at 160 °C. In addition, a good thermoelectric response was shown.