Technologies are generally described for controlling temperature using compounds capable of photoisomerization. In some examples, a temperature control apparatus includes a first receiving unit configured to contain a compound capable of photoisomerization, a second receiving unit configured to contain the compound capable of photoisomerization, a first filter configured to pass first light from a first light source, and a second filter configured to pass second light from a second light source. Further, the first and second receiving units are coupled to each other so that the compound capable of photoisomerization may be circulated between the first and second receiving units, and the compound capable of photoisomerization in the first receiving unit and the second receiving unit is photoisomerized by at least one of the first light and the second light.