|Full name||Francesc Xavier Arnau Grabulosa|
|Date of birth||23 May 1975|
|Place of birth||Les Planes, Spain|
|Height||Script error: No such module "convert".|
Born in Les Planes d'Hostoles, Girona, Catalonia, Arnau was a youth graduate from La Liga powerhouse FC Barcelona. He made his first-team debut in 1996–97, in a 3–3 home draw against Atlético Madrid on 9 November 1996.
For the 2001–02 campaign Arnau moved to Málaga CF for € 2.1 million, also playing second-fiddle until the departure of Pedro Contreras to Real Betis in 2003. He would eventually become club captain, but lost his job in 2007–08 in the second division, to Iñaki Goitia.
In the 2009 summer Goitia was sold also to Betis, but Málaga also acquired Gustavo Munúa and Roberto Santamaría, so Arnau was demoted to as low as third-choice in the 2009–10 season, eventually finishing backup to the Uruguayan but without making one single official appearance.
After Munúa's departure, Arnau played the first game of 2010–11 – a 1–3 home loss against Valencia CF – as Rodrigo Galatto was not yet eligible. He continued appearing regularly for the club in the following weeks after the Brazilian performed poorly and another new signing, Rubén, went down with an injury.
On 21 May 2011 Arnau played his last match as a professional, coming on as a substitute for Willy Caballero in the last minutes of a 1–3 home defeat against his first club Barcelona, with Málaga finally retaining its top division status. After retiring at the age of 36, he continued working with his last team, as a youth coach, alongside former club teammate Salva.
- UEFA Cup Winners' Cup: 1996–97
- La Liga: 1998–99
- Copa del Rey: 1996–97
- Supercopa de España: 1996
- Spain U21
- Valencia shrug off departures; ESPN Soccernet, 28 August 2010
- Second XI ease to win; ESPN Soccernet, 21 May 2011
- El Málaga cuenta con Arnau y Salva como entrenadores de cantera para La Academia (Málaga counts with Arnau and Salva as youth team coaches for the Academy); La Opinión de Málaga, 23 March 2011 Invalid language code.
- "1998: Francesc Arnau". UEFA.com. 1 June 1998. Retrieved 20 February 2015.
- "Barça de titanes" [Titanic Barça] (in Spanish). El Mundo Deportivo. 29 June 1997. Retrieved 20 February 2015.
- "Título con súper-susto" [Title with mega-scare] (in Spanish). El Mundo Deportivo. 29 August 1996. Retrieved 20 February 2015.
- "1998: Iván Pérez applies finishing touch". UEFA.com. Retrieved 20 February 2015.