Until recently Airport Buses were definitely the best way to get to the city centre if you were arriving at Terminal 1 (T1) as the RENFE railway station is at Terminal 2.
However, with the opening of the new L9 Metro Line in March 2016, there is now a metro service from both terminals, which although it involves a change of line takes you straight to the city centre for €4.50.
Buses and coaches also go to other destinations in Catalonia and Spain, and catching a coach directly at the airport is often more convenient
A train to these destinations would generally involve a change in Barcelona City Centre so Barcelona Airport Coach services are particularly appropriate for destinations in south of the airport, such as Castelldefels, Sitges or Salou.
The best known Barcelona Airport Bus Service connecting Barcelona Airport with Barcelona City Centre is the Aerobus and there are two separate Aerobús Services running from terminals T1 and T2 respectively.
Aerobús A1 serves Terminal 1 and A2 serves Terminal 2 and the main stops (shown on the graphic below) are Barcelona Airport (Terminal 1 and Terminal 2), Plaça Espanya, Gran Via-Urgell, Plaça Universitat and Plaça Catalunya.
Both Aerobúses run about every 5 minutes leaving Plaça Catalunya from 5.30 am to 00.30 am and leaving Terminals 1 and 2 from 6.10 am to 1.05 am.
Tickets are more expensive than regular buses and a single costs €5.90 and a return costs €10.20 and is valid for 15 days after the date of purchase.
You can buy tickets from the driver (cash only), from vending machines which also accept credit cards inside the terminal buildings or online from www.aerobusbcn.com
Please note that both Aerobuses cover the some stops in Barcelona, so if you're going to the Barcelona Airport from the City Centre, you should pay particular attention to which of the Terminals (T1 or T2) is the terminus.
Regular Barcelona Airport Transport Bus services are provided by the main Barcelona Transport organisation Transports Metropolitans de Barcelona (TMB).
TMB-operated bus services are considerably cheaper than the Aerobús and the T10 and the Barcelona Card are both valid on TMB buses.
Daytime services to Barcelona city centre run from about 6 am to 10 pm but only serve Plaça Espanya so you will have to catch the Metro to get to your final destination.
Night bus services run from about 11 pm to 5 am and will take you to Plaça Catalunya in the centre of Barcelona.
Here is a list of bus services from the Airport including destination and number:
A number of private bus and coach companies provide Barcelona Airport Bus services to other cities and towns in the Catalonia and the rest of Spain.