Gas chromatography oven

In a gas chromatography oven the heated enclosure should be of low thermal mass to permit more rapid programmed temperature changes and to provide guide oven cooling for work on the columns between analyses. Also, easy access to the columns is desirable. An oven is provided comprising a heatable enclosure having a door 5 and one or more chromatograph columns 24 supported in a predetermined position relative to a wall 10 of the enclosure. The wall 10 extends in a direction transverse to the door opening and, with the door open, the wall is movable from a first position in which the columns are within the enclosure to a second position in which the columns are outside the enclosure and the wall is supported by the oven. Access to the columns is now not required within the enclosure which can be smaller and hence of lower thermal mass.