DMV.org provides links to several study guides for the test required to get a hazmat endorsement on a commercial driver's license. In addition, the site provides information on how to prepare for a commercial driver's exam and the application requirements for the license.
In addition, several websites, including Trucker Country, offer practice tests for the hazmat endorsement to a commercial driver's license. Some of these sites, such as Trucker Truth, also provide training materials. The practice tests provided on these sites feature questions similar to those on the actual written test. Transport of hazardous materials requires a special endorsement in most states. In addition, the federal government requires a background check performed by the TSA.