The effect of ultrasonic (US) pre-treatment on the drying characteristics of Loligo vulgaris (European squid) was investigated in oven and vacuum oven. In each method, effective moisture diffusivities (D-eff) and activation energies (E-a) were determined. According to mathematical modeling with fifteen models, the Midilli and Kucuk model best fit the oven and US vacuum oven; Alibas and parabolic best fit the vacuum oven and US oven, respectively. D-eff values were found to be between 0.612-1.84 x 10(-10) m(2)/s. Vacuum increased the E-a values, and the highest E-a was found as 47.67 kJ/mol with vacuum oven. The lowest Delta E value was obtained with the US vacuum oven. As a result, it was observed that US pretreatment was beneficial in color protection while increasing the drying time, whereas vacuum shortened the drying time and was effective in color protection.