Metallic micrometamaterials exhibit exceptional specific strength and energy dissipation capacity, yet their mechanical behavior under extreme thermomechanical conditions remains poorly understood. Here, we uncover deformation mechanisms in metallic microlattices subjected to combined thermal and mechanical extremes. Copper microlattices were fabricated via localized electrodeposition process with submicron spatial resolution and, for the first time, compressed at cryogenic (-150°C) and room tem