Various methods for the evaluation of J-initiation toughness have been compared by conducting investigations on Mo and Cr-Mo steel at different temperatures (i.e., 30 to 460°C) by employing the single-edge-notch bending configuration. The methods investigated include ASTM Standard E 813, a method proposed by the European Group on Fracture (EGF), methods based on a stretch zone approach, and a proposed method of the Japan Society of Mechanical Engineers (JSME). The blunting line approach for toughness determination has been investigated in detail in the light of various propositions made by other investigators, and an equation for the blunting line has been proposed based on the findings from the present work as well as from literature data. A J-resistance curve based on mid-thickness crack growth combined with the stretch zone approach for the blunting line appears to provide a mose comsistent method for toughness determination.