An aqueous-based composition and process for removing hardened photoresist and/or bottom anti-reflective coating (BARC) material from a microelectronic device having same thereon. The aqueous-based composition includes at least one chaotropic solute, at least one alkaline base, and deionized water. The composition achieves high-efficiency removal of hardened photoresist and/or BARC material in the manufacture of integrated circuitry without adverse effect to metal species on the substrate, such as copper, and without damage to low-k dielectric materials employed in the microelectronic device architecture.