In this paper, a new specimen called mixed mode double cantilever beam (MMDCB) was developed for the mixed mode fracture characterization of adhesives under high displacement rates. The MMDCB specimen was designed using finite elements simulations in order to determine the fracture toughness for a mode mixity in the plane I+II+III. Firstly, results from MMDCB specimens tested under quasi-static loading were experimentally compared to a reference single leg bending test. The test results, obtained with the two different specimens, exhibit consistent evaluations of the mixed mode fracture toughness. Secondly, the MMDCB specimen testing under asymmetric high displacement rate was validated through explicit simulations. The corrected beam theory with effective crack length was extended to the analysis of MMDCB specimens tested under high displacement rate. It was numerically proved to accurately determine the mixed mode fracture toughness under a displacement rate up to 1 m/s.