HX
HX, Hx, Hx, or hx may refer to:

Businesses and brands
 Dolby HX and Dolby HX Pro, dynamic range headroom extension systems for analog recording on magnetic tape
 Hummer HX, a concept automobile produced by HUMMER
 Rheinmetall MAN Military Vehicles (RMMV) HX range of tactical trucks, a range of in-production military tactical trucks 
 Hong Kong Airlines (IATA code)

Other uses
 Hx or hx, a digraph in the Esperanto x-system orthography, representing the consonant sound  or , normally spelled as Ĥ or ĥ in the Esperanto alphabet
 .hx, the file extension for the Haxe programming language
 HX (convoy), a convoy code used during World War II
 Hx or Hx, medical history
 HX postcode area, UK, covering Halifax, Elland, Hebden Bridge and Sowerby Bridge in England
 Short name for Harolds Cross an inner suburb on the south side of Dublin, Ireland.
 Hydrogen halide, a chemical compound
 Informal engineering shorthand for heat exchanger