Òscar has been commissioned among others by the Aldeburgh Festival, the Philharmonia Orchestra for its Music of Our Time series, the Schubert Ensemble, Orchestra of the Swan, Valencian Music Institute, Trio Rebec, Antares Ensemble and percussion group Kontakte.

His music has been premiered at the Wigmore Hall, Royal Festival Hall, Queen Elizabeth Hall, Purcell Room, Sir Adrian Boult Hall, Yale University's Sprague Hall, Palau de la Música de Valencia, and the Auditorio de Galicia with the Real Filharmonia de Galicia Orchestra; it has been radio broadcasted in Spain, Mexico, Denmark and the USA; and has also featured in festivals such as the City of London Festival, Manchester QuartetFest, the European Congress of Conservatoires, ENSEMS-València or the Encuentro Internacional de Compositores in Mallorca.

His orchestral piece Le Vitrail Englouti was premiered at the Royal Academy in a project mentored by Yan-Pascal Tortelier. Selected by the Yale University composition faculty to take part in a Cross-Atlantic Partnership project -involving a guest visit and concert at New Haven- he has also been resident composer with the Joven Orquesta Internacional Ciudad de Oviedo (2006), in Cove Park (2008), and was one of the two commissioned composers (alongside Tomás Marco) in the Burgos Summer Festival 2009 . Recent engagements include the Southbank premiere of Five Words, Three Phrases , and the Spanish premiere of The Thinking Machine in the International Conference on Contemporary Music 2010 in A Coruña.

Òscar was appointed in 2011 Principal Conductor of the City of Salamanca Youth Orchestra (Spain). He also conducts the Junior Orchestra at The Yehudi Menuhin School, where he teaches since 2006. As guest conductor with various contemporary ensembles, he has appeared in the Círculo de Bellas Artes de Madrid, the Segovia Summer Festival, Ávila, GSMD New Music Festival and the London Contemporary Dance School.