Environmental testing is a process of subjecting a test specimen to various temperature and humidity conditions in order to determine the effect of these conditions on the test specimen. Often, this conditioning is conducted prior to other tests such as mechanical or package performance testing in order that the test specimen be exposed to a full range of potentially harmful temperature and humidity levels.

The testing is conducted in an environmental chamber designed to maintain tight controls over both temperature and humidity as well as the rates at which these quantities are changed. The test levels chosen and the rate of change between these levels are typical of what might be encountered during an extreme distribution cycle, for example, or storage for an extended period of time.

It is generally recognized that thermal stresses are some of the most severe that a product or package will be exposed to during its entire lifecycle. In addition, any hydroscopic elements of a product or package system will change their strength characteristics as they absorb or release moisture. Both operational and non-operational testing is common.