on 9 january 2020, de tomás returned to his country's top flight, signing for rcd espanyol on a contract lasting until 2026. the transfer fee of €20 million was a new record for the club from barcelona, nearly doubling the €10.5 million they paid for matías vargas; benfica retained 20% of his future transfer fee. three days after joining, he made his debut away to ud san sebastián de los reyes in the third round of the national cup, coming on in the 61st minute for jonathan calleri and wrapping up a 2–0 win. on 19 january, he started in his first league game and scored the decisive goal of a 2–1 victory at villarreal cf.