3H is a symbol for tritium. 3H or 3-H may also refer to: * 3H, or British Rail Class 205 * 3H Movement, a liberal Turkish youth organization * 3H Biomedical, a Swedish biotechnology company * Mu-3H, a model of Mu (rocket family) * Yuri 3H, a Broadcasting Satellite (Japanese) * SSH 3H (WA), alternate designation for Washington State Route 27 * Old Natchez Trace (230-3H); see Old Natchez Trace segments listed on the National Register of Historic Places