金属键是在化学键的一种，主要在金属中存在，一些原子簇化合物中也存在金属键。由离域电子及排列成晶格状的金属离子之间的静电吸引力组合而成。

由于电子的自由运动，金属键没有固定的方向，因而是非极性键。

金属键决定了金属许多物理特性，如强度、可塑性、延展性、传导热量、导电性和光泽。例如一般金属的熔点、沸点随金属键的强度而升高。离子半径越小，金属键越强。

Metallic bonding arises from the electrostatic attractive force between conduction electrons (in the form of an electron cloud of delocalized electrons) and positively charged metal ions. It may be described as the sharing of free electrons among a lattice of positively charged ions (cations). Metallic bonding accounts for many physical properties of metals, such as strength, ductility, thermal and electrical resistivity and conductivity, opacity, and luster.