Depending what time one is arriving at Porto Francisco Sá Carneiro Airport (OPO), Transdev now also operating a bus shuttle from the airport to Garagem Atlantico in Rua Alexandre Herculano which is the main Porto bus station for Rede-Expressos.pt and CiteExpress.eu.
The service operates almost hourly between 08:00 (to airport)/ 08:25 (from airport) until 19:00 (to Airport)/ (19:25) from airport.
Details here:http://www.transdev.pt/aeroportoporto/
Outside these hours, one can use the Metro to Bolhão and then walk the 600m to the Bus Station. Be aware that the Airport Service operates only 2/3 times an hour.
