Abstract Effect of extrusion cooking using different corn starch contents on the physicochemical properties (expansion ratio, bulk density, color, hardness, protein in vitro digestibility, crude protein content, thermal properties and microstructure) of tuna meat-based extrudates was investigated. The results showed that the increased corn starch content led to darker, greener, yellower and lower crude protein content of extrudates, but no significant difference was observed in expansion ratio, bulk density and hardness. The lowest protein in vitro digestibility of 82.83±0.39% appeared when the corn starch content was 20 wt%. The results of DSC revealed that tuna meat with corn starch content of 30 wt% and 20 wt% had the highest and lowest denaturation temperature of 99.4oC and 81.9 oC, respectively. The results of SEM indicated that the extrudate with 30 wt% corn starch content possessed the more integrated and distinct muscle fibers. Besides, the acceptability of the extrudate with 30 wt% corn starch content was significant better than others (p˂0.05). These results revealed that the tuna meat-based extrudates using 30 wt% of corn starch exhibited desirable physicochemical properties.