A slidable dual-axis hinge assembly has a sliding leaf and a stationary leaf. The sliding leaf has two detents and an outer pivot formed on a pivoting end of the sliding leaf and pivotally mounting the sliding leaf in a cover of a portable electronic device. The stationary leaf has an inner pivot formed on a proximal end of the stationary leaf and pivotally mounts the stationary leaf in a base of the portable electronic device, and has two slide brackets engaging the detents and defining two sliding grooves oppositely therein and being mounted around the side edges of the sliding leaf to allow the sliding leaf to slide relative to the stationary leaf. Thereby, the cover of the portable electronic device pivots relative to the base in two different positions.