An alkanediol, composed of alkane and diol, are a group of substances consisting of linear or branched hydrocarbon chains containing exactly two hydroxy groups at different positions. They are a subgroup of the diols and contain no other heteroatoms or multiple bonds.

Example of a 1,2-diol (Ethyleneglycol, top),
a 1,3-diol (1,3-Propanediol, middle)
and a 1,4-diol (1,4-Butanediol, bottom).