It originated as an instrumental by Reeves Gabrels called "Moondust", which Bowie and Brian Eno stripped down and used to form the final track.

An industrial rock and electronica number influenced by the Pixies and Nine Inch Nails, the song contains a hypnotic sound, with synthesisers, loops and distorted guitar lines.

For its release as the third and final single from Outside in February 1996, "Hallo Spaceboy" was remixed by the duo Pet Shop Boys, who added a disco edge and lyrics referencing the Major Tom character from Bowie's "Space Oddity".

"[3] The final track features Bowie, Eno, Gabrels, guitarist Carlos Alomar, bassist Yossi Fine, pianist Mike Garson and drummer Joey Baron.

[1] Characterised by commentators as industrial rock and electronica,[3][6][7] Pegg describes "Hallo Spaceboy" as "a hardcore maelstrom of sci-fi noise, hypnotic high-speed drumming and an insistent, speaker-hopping four-note guitar riff".

[5] Featuring synthesisers, loops and distorted guitar lines,[1] a few reviewers compared the song's sound to Bowie's 1974 album Diamond Dogs and his work with the rock band Tin Machine.

[4][8][10] Some of the words and ideals, such as "chaos", "dust" and "hallo", and visions of a science fiction apocalypse were recycled from Tin Machine's "Baby Universal" (1991).

[4][8] Bowie intended "Hallo Spaceboy" to be his next single after "Strangers When We Meet", performing the song twice in Birmingham and again on Jools Holland's Later... in late December the same year.

[15] Tennant, a lifelong Bowie fan, stripped the song's anger with electronics and added Pet Shop Boys' signature backing vocals to the mix.

Combined with the original only containing a single verse, and a lyric including feelings of alienation, Tennant and bandmate Chris Lowe added lyrical fragments from Bowie's 1969 song "Space Oddity", using a Gysin-style cut-up technique, to create a second verse: "Ground to Major, bye bye Tom / dead the circuit, countdown's wrong / Planet Earth is control on?

[22] The CD single was packaged with a reissue of "The Hearts Filthy Lesson" and live renditions of "Under Pressure" and "Moonage Daydream",[4][22] recorded on the Outside Tour on 13 December 1995 in Birmingham.

[33][34] The music video for "Hallo Spaceboy" was directed by longtime Bowie director David Mallet, mixing shots of both Bowie and Pet Shop Boys into a rapid-fire montage of Cold War era retro-footage of science fiction film clips, atomic bomb testing footage and television advertising clips.

[8][21] AllMusic's Christian Huey said that the song was "the most successful spin since [1980's] Scary Monsters (and Super Creeps) on his recurring 'urban nightmare' motif.

[43] Paul Lester from Melody Maker said, "'Hallo Spaceboy', drenched in the theatrical mockneyisms that begat Damon Albarn and Brett Anderson, is trip hoppy (dub it up, Portishead!

[49] "Hallo Spaceboy" featured regularly on Bowie's setlists throughout 1996 and 1997, and made return appearances during his 2000 summer shows, 2002 Heathen and 2003–2004 A Reality tours.