Butane, also called n-butane, is the unbranched alkane with four carbon atoms, CH 3 CH 2 CH 2 CH 3 . Butane is also used as a collective term for n-butane together with its only other isomer, isobutane (also called methylpropane), CH(CH 3 ) 3 .

Butanes are highly flammable, colorless, odorless, easily liquefied gases. The name butane was derived by back-formation from the name of butyric acid.

Image:Butane-2D-Skeletal.svg|n-Butane Image:I-Butane-2D-Skeletal.svg|i-Butane