Hi,

I am wondering whether it is possible to book tickets from Madrid to Benidorm, at the airport a day in advance.

Thanks,
Steven

You can call the bus line to make a reservation for the following day (not for same day travel) if you can do so in Spanish. You may be able to make a reservation on the Internet: Viajes Julia, DBA Eurolines-Spain has Madrid-Benidorm service and I have in the past made a reservation with that company online. Generaly you have to pick up your tickets an hour and a half before departure time or your reservation will be cancelled.

You can book your tickets online at Alsa/Enatcar website which is available in English. As Eddie said, online reservations have to be made at least 24 hours in advance. Otherwise, you'll have to go to the bus station (Estación Sur de Autobuses at Méndez Álvaro) to buy the tickets.