A front insert for a ski mountaineering boot has first and second heads, positionable on lateral portions of a front part of the boot, a first housing in the first head, a second housing in the second head, and two contact elements with respective holes for coupling with respective hooking elements of a binding. The housings and respective ones of the contact elements are reciprocally conformed so as to enable the contact elements to displace from internal positions with respect to the housings, towards the outside, so that the contact elements orient with respect to the housings so that the holes can misalign from an alignment axis to maintain the contact with the hooking elements following a rotation of the ski boot with respect to the ski.