Statement of Purpose: Hydrogen sulfide (H2S) serves as a gaseous signal-transmitter molecule in the human body that regulates inflammation, relaxes vascular smooth muscles, promotes angiogenesis and mediates neurotransmission. With the discovery of the biological significance of H2S, the potential for H2S-based therapies has attracted growing attention. However, due to its volatile nature and a short half-life under physiological conditions, development of H2S delivery systems, which enables the release of H2S at the site of interest in a controlled manner are needed in order to explore its full therapeutic potential. One common approach is to use H2S donor compounds, such as anethole dithiolethione (ADT) derivatives, which generate H2S under physiological conditions. However, the fast and uncontrolled rate of H2S release, toxic side effects of the donor compounds and/or their decomposition byproducts as well as rapid renal clearance remain as the major problems associated with the use of small H2S donor compounds. To address this issue, we developed nano-sized gas donors based on polymeric micelles (H2S donor micelles, Figure 1) which enable sustained H2S release under physiological conditions. Here, we report design, synthesis and characterization of polymeric H2S donor micelles containing anethole dithiolethione (ADT) moieties. Furthermore, the anti-cancer activities of these micelles were evaluated in the in vitro cell culture assays as well as the in ovo chick chorioallantoic membrane (CAM) assay.