Factories manufacturing mercury (Hg)-containing devices often outflow exhaust gas with a high concentration of Hg and face the risk of liquid Hg leakage. Herein, nanosized CuSe was prepared and employed for elemental mercury (Hg-0) capture and the emergency disposal of liquid Hg from accidental leakage. CuSe exhibited an excellent He capture performance at room temperature. The He concentration could be efficiently reduced from 1500 to below 1 mu g.m(-3) under a gaseous hourly space velocity of 1.2 x 10(5) h(-1). The adsorbent amount of CuSe was about 210.8 mg.g(-1), which was about 219.5 times higher than that of a sulfur-functionalized activated carbon sorbent used exclusively for He removal. CuSe exhibited excellent adaptability at different temperatures and high-humidity surroundings. CuSe could effectively stabilize the leaked liquid Hg. The initial liquid Hg adsorption rate for CuSe was high, up to 69.1 mu g.g(-1).min(-1), 138-2303-fold greater than that for other adsorbents reported in the literature. The impressive performance of CuSe for Hg-0 immobilization was primarily attributed to the strong affinity of Se for Hg. The adsorption product of Hg (i.e., HgSe) exhibited sufficient thermal stability, which guaranteed the long-term storage of Hg-laden CuSe.