Production for the album is handled by Fermín Ugarte, Ramón Evar Peaguda, Luis Tomás La Madrid and Dillom himself.

Dillom rose to fame in 2018 with the self-produced track "Dripping" and founded the creative team Rip Gang, alongside fellow musicians Ill Quentín, Muerejoven, Odd Mami, Taichu and Saramalacara.

Post Mortem was described as an "eclectic" mix of hip hop, horrorcore, pop and rock, with elements of industrial, experimental and trap.

[5][6] Consisting of 18 tracks, it is a concept album about "overcoming the fear of death" and addresses topics such as his childhood, family, love, fame and existentialism.

[11][12] This part of the album was described as the "darkest", with ninth track "Side" noted for its personal lyrics, touching upon themes such as his mother.

Fellow Rip Gang member Muerejoven is featured on "Coach", a trap song described as a "more straightforward rapper [type of] track".

[17] The album's final section opens with "Toda la Gente", a choir and piano interlude reminiscent of 80s Argentine rock, most notably Fito Páez.

"Reality" was compared to Marilyn Manson, while "Rocketpowers", featuring Rip Gang member Saramalacara, was described as a "fun", blink-182-influenced post-punk track.

Indie Hoy praised the cover as "disturbing and fascinating" and described it as a "visual fable where Dillom is at the center of a spiritual session surrounded by ghosts and creatures creeping on the musician".

[23] "Across 18 tracks, we meet with a carousel of styles and genres [...] And this is, precisely, the record's greatest achievement: not for one moment it sounds predictable and that, these days, it's really complicated to find."

Malena Sabanes Niccolini from El Destape praised the album and called it "one of the best of the year", while Buenos Aires platform enAgenda lauded Dillom as "the scene's most original artist".

Lucas Santomero from Indie Hoy described Post Mortem as "complete, overwhelming and, for some, unexpected [...] Much bigger than a simple trap record".

[33] All songs written and produced by Dillom, Fermín Ugarte, Ramón Evar Peaguda and Luis Tomás La Madrid, unless noted otherwise.