Kooij started his musical career at 6 years as a choir boy. However he started his musical studies as a violin student. He came back to singing, with tuition from Max van Egmond at the Sweelinck Conservatorium in Amsterdam which led in 1980 to the award of the diploma for solo performance.
In 2002 he founded together with Monika Frimmer, Christa Bonhoff and Dantes Diwiak a quartet Tanto Canto to sing rarely performed music a cappella, with piano or with ensemble. The quartet recorded in 2005 excerpts from the collections Augsburger Tafel-Confect (short for: Ohren-vergnügendes und Gemüth-ergötzendes Tafel-Confect, in English: Augsburg Table Confectionery, Pleasuring the Ears and Delightful to the Soul) of the composers Valentin Rathgeber and Johann Caspar Seyfert.
1995-2008 : Bach's complete cantatas (Bach Collegium Japan)
Solo recitals
Mein Herz ist bereit German Solo cantatas for bass, violin and b. c. from the 17th century. - BruhnsMein Herz ist bereit, Buxtehude, Tunder, Pachelbel, Rosenmüller, J. P. Krieger, BiberNisi Dominus CordArte Ensemble, Pan Classics PC10211 2005
De profundis clamavi – Weckmann, Bruhns, Geist, Buns, J. C. Bach. Armonia Sonora, Ramée 2007
Harmonia Sacrae – Tunder An Wasserflüssen Babylon, MederGott hilf mir; Ach Herr, strafe mich nicht mit deinem Zorn, Christoph Weckmann Lamentatio Wie liegt die Stadt so wüste, Christoph BernhardSie haben meinen Herrn hinweggenommen, Buns Obstupescite Peter Kooij, Hana Blažíková, L'Armonia Sonora, dir. Mieneke van der Velden, Ramée. 2009
