Technical Abstract: Cinnamaldehyde was delivered in emulsion form using Acetem 90-50K as a carrier and Tween 60 as emulsifier. Cinnamaldehyde interacted with Acetem 90-50K by forming H-bonds. The effect of disperse phase characteristics on storage stability, physical and antimicrobial properties was investigated. Storage test of emulsions was carried out for 15 days at two temperatures (22 and 4°C). Emulsions and nano-emulsions showed higher stability at 22 °C than at 4°C. Nano-emulsions displayed excellent stability vs. creaming and coalescence after 15 days storage at 22 °C (z-avg<100nm). Physical properties were greatly affected by droplet size and concentration. Emulsions became less viscous, more transparent and darker as the droplet size or concentration decreased. The antimicrobial activity was measured against Listeria monocytogenes and Escherichia coli. Escherichia coli was highly resistant to cinnamaldehyde compared to L. monocytogenes. Incubation with cinnamaldehyde at 2.5 mM caused the complete inactivation of L. monocytogenes after 1 day and of E. coli after 9 days. There was no difference in the antimicrobial effect of cinnamaldehyde due to different droplet sizes (~80 nm and ~5000 nm).