H line

H line may refer to:
 * H Line (RTD), a light rail line in Denver and Aurora, Colorado, U.S.
 * H Line, a portion of the North Carolina Railroad between Greensboro and Cary, North Carolina, US
 * H (Los Angeles Railway), former streetcar service
 * Line H (Buenos Aires Underground), a metro line in Buenos Aires, Argentina
 * The 404.7nm emission band from a Mercury-vapor lamp
 * The calcium H line, an absorption line in the Sun's spectrum at 396.9nm
 * Pencil skirt, sometimes called a H-line skirt