The following month, the strings were recorded and performed by the Orchestra of St John's in a church near the band's studio, arranged by the multi-instrumentalist Jonny Greenwood on an ondes Martenot.

[13] The song was inspired by a dream Yorke had on the night of this show,[14] in which he was running naked down Dublin's River Liffey and being pursued by a tidal wave.

[15] According to the guitarist Ed O'Brien, "How to Disappear Completely" was inspired by the RDS performance and the stress the band members, especially Yorke, experienced on tour.

"[17] In an interview with Terry David Mulligan in Canada in July 1997, Yorke said he had written a song the previous month with the chorus: "I'm not here / This isn't happening".

[26] Melody Maker likened one version in a 1998 review to Radiohead covering Unbelievable Truth,[27] an acoustic band led by Yorke's younger brother, Andy.

[33] According to some accounts, the song was dedicated to the Manic Street Preachers guitarist Richey Edwards,[34][35] who disappeared in February 1995 and was declared dead in November 2008.

[30] On 2 December 1999,[41] with assistance from the producer, Nigel Godrich,[5] Greenwood, the only Radiohead member trained in music theory,[49] began composing the string arrangement.

[58] "How to Disappear Completely" is an acoustic-driven ballad backed by "forlorn" strings and "compelling" guitar effects,[59][4] with elements of orchestral and ambient music.

[67] Jazz Monroe of The Guardian categorised the song as avant-garde balladry, calling it a "masterpiece" that "orchestrates a stage-fright reverie with fragments of Robert Wyatt and Penderecki".

[71] It features strummed acoustic guitar,[72] a Chris Squire-influenced bassline,[73] and a base layer of strings that progresses to "paranoid" electronica and "lush" orchestration,[72] influenced by the music of the Moody Blues.

[73] The song is played in the key of F♯ minor in a 68 time signature with a tempo of 102 beats per minute (BPM),[74][75] while Yorke's vocals span a range of C♯4 to A5,[75] which he performed in a "long-drawn-out" falsetto.

[50] Jamie Kahn of Far Out praised the string section for blending with acoustic guitar and Yorke's "haunting" vocals to create an "eclectic, harmonious" mix.

[86] James Oldham of NME wrote that the chorus, "I'm not here / This isn't happening", reflects Yorke's mental state of what he and the rest of the band experienced from their tour for OK Computer.

[95][96] An audio live version, recorded on 15 November 2000 for broadcast on BBC Radio 1's Evening Session,[97] was included on the Kid A "Special Collectors Edition" reissue in 2009.

[100] The music supervisor, Alexandra Patsavas, recalled: Jason Katims and Ron Moore were keen to get the track for an episode, but Radiohead for television—even great television—seemed so out of reach.

[104] In a 2000 article published prior to the release of Kid A, Melody Maker's Andre Paine described "How to Disappear Completely" as "several minutes of music that sounds like the Smiths produced by DJ Shadow".

[105] Reviewing Kid A in 2000, NME's Keith Cameron wrote that the song sees Radiohead's "return to the big ballad template, as massed strings swoon and Yorke's voice soars transcendentally for the first time".

[106] The Rolling Stone critic David Fricke wrote that the song "moves like an ice floe: cold-blue folk rock with just a faint hint of heartbeat.

"[107] Brent DiCrescenzo of Pitchfork stated that the song "boil[ed] down [OK Computer tracks] 'Let Down' and 'Karma Police' to their spectral essence", claiming it "comes closest to bridging Yorke's lyrical sentiment to the instrumental effect.

"[64] Billboard called "How to Disappear Completely" "haunting", noting that "vocalist Thom Yorke is as tortured as ever, proclaiming 'I'm not here/This isn't happening' [...] as if he'd already vanished long ago.

[109] Simon Reynolds of Uncut described the song as a "missing link" between Scott Walker's orchestral music and the "swoonily amorphous" ballads on My Bloody Valentine's album Isn't Anything (1988).

[80] He also compared the acoustic guitar, which "slowly builds to an operatic emotional climax", to previous Radiohead songs such as "Fake Plastic Trees" and "Exit Music (For a Film)".