İsveçli death/thrash metal grubu IMPIOUS 1994 yılı Nisan ayında Valle Adzic ve Martin Akesson tarafından kurulmuştur. Grup; grupta devamlı çalacak bir davulcu bulmakta güçlük çekiyordu, bu yüzden gruptakilerin bir arkadaşı olan Johan grubun o dönemlik davul ihtiyacını doldurdu. Bundan kısa bir süre sonra Robin Sörqvist gruba bassçı olarak katıldı. Bundan sonra IMPIOUS sahneye ilk kez "Infernal Predomination" adlı demolarıyla 1995 yazında çıktı. Tekrar kısa bir süre sonra grubu terketmek zorunda kaldı. Grup; grupta devamlı olarak çalabilecek bir davulcu bulmanın bu kadar zor olacağını tahmin etmiyordu. Yine hiç bir davulcu bulunamıyordu bu yüzden grup eskisi gibi arkadaş çevresinden Marko adında bir davulcuyu geçici olarak bünyesine kattı. Bu sayade grup 2. kez demo hazırlıklarına başladı ve mayıs 1996 da ikinci demoları olan "The Suffering" adlı parçayı Andy La Rocque ile kaydetti.

Bu 2. demo kaydından hemen sonra grup, en sonunda aradığı davulcuyu buluyor. Ulf Johansson adlı davulcuyla birlikte 1997 yazında 3. demo "Promo ´97" de kayda alındı. Fakat bu demo hiç piyasaya sürülmedi. (buraya kadar çevirdim çevirdikçe ekleme yapacağım - wahDEATH!)
At the same recording session, the band recorded a Sepultura cover for the tribute album "Sepulchral Feast". IMPIOUS covered the song "Inner Self". "Promo ´97" resulted in a record deal with Swedish label Black Sun Records, and in december ´97 IMPIOUS recorded their debut album "Evilized" in Sunlight Studios with producer Tomas Skogsberg. The album was released in the summer of ´98. Later that year in october the band entered Los Angered Recording once again, but this time to record a Metallica cover for the tribute album "Metal Melitia III". The song "One" was covered.

´99 was a quite lame year for IMPIOUS, but in January ´00 the band recorded their second album in Studio Mega with engineer Chris Silver. Unfortunately it took almost a year for Black Sun to release the album. Anyway, in the summer of ´00 IMPIOUS decieded to make some drastic line-up changes. Martin, who had always sang and played the guitar, quit playing the guitar to concentrate on the vocals. Robin switched from bass to lead guitar. And since Robin actually is a better guitar player than both Martin and Valle, this was a smart move. So, there was an empty gap to fill, and a friend called Erik Peterson was asked to join the band to play the bass. He accepted.

In March ´01 IMPIOUS recorded a four song promo in Studio Mega. The promo was sent to different labels with the intention to get a new deal. After looking at offers from some labels, IMPIOUS decided to sign a deal with Hammerheart Records (now called Karmageddon Media).

In February ´02 drummer Ulf Johansson left the band, just five weeks before the recording of the new album. No tears shed. IMPIOUS immediately braught in Mikael Norén, and in just a few weeks he learned all the 10 songs for the album. So in March ´02 the band recorded their third album "The Killer", once again at Studio Mega with Chris Silver. Also a MCD was recorded later that year, including "The Deathsquad" from the album "The Killer" plus a re-recorded version of the song "Extreme Pestilence" from "Evilized", plus three covers from Metallica, Running Wild and Mötley Crüe, and two songs from their "Promo 2001". That MCD was released in January ´03 when the band went on a European tour together with Necrophobic and Satariel. The tour turned out to be a very successful trip since IMPIOUS managed to confirm as being a very intense and powerful liveband.

In February ´04 IMPIOUS pays some respect to the fathers of death metal: Possessed, by appearing on the tribute album "Seven Gates Of Horror" together with bands as Cannibal Corpse, Sadistic Intent, Vader, Sinister, Angel Corpse and Amon Amarth. Also in February ´04 IMPIOUS also signed a worldwide deal with legendary Metal Blade Records.

During the period May-July IMPIOUS recorded their fourth album "Hellucinate" at Studio Mega, except all vocals and solos which were recorded at Valle Adzic's own Deadline Studio. IMPIOUS will do a European tour in October with label mates Amon Amarth and Disillusion.