H. I. Thorsteinsson (Hreiðar Ingi Þorsteinsson) started composing music at the age of fourteen. He obtained his degree in musical education from the Reykjavík College of Music in the spring of 2001 and his BA degree in composition from the Iceland Academy of the Arts in 2007. His teachers in music composition were Þorkell Sigurbjörnsson and Hróðmar I. Sigurbjörnsson. In the spring of 2008 Thorsteinsson completed a final examination in singing from The Reykjavík Academy of Singing and Vocal Arts, with baritone Alex Ashworth as his teacher and the following year he received two postgraduate degrees, in composition and in choral conducting, from Jyväskylän ammattikorkeakoulu in Finland, with composer Erkki Raiski and choral conductor Rita Varonen as his supervisors. Then in the spring of 2011 he earned a Masters degree in composition from Eesti Muusika-ja Teatriaakadeemia in Estonia, graduated with distinction under the direction of Toivo Tulev. Thorsteinsson is a member of the Association of Icelandic Composers and conducts two mixed choirs: The Choir of Hamrahlíð College and Ægisif.