Express Bus Services between Lisbon and Obidos are operated by Rodoviária do Tejo. They operate Lisbon Campo Grande (Metro) and take about 1 hr. 10 minutes.
Click on these links for the current timetables.
Lisbon - Obidos http://www.rodotejo.pt/horarios/todosresultados/5227/3260/1
Obidos - Lisbon http://www.rodotejo.pt/horarios/todosresultados/3260/5227/1
Note the ones marked "Aos Sabados, Domingos E Feriados." operate only at week-ends and on public holidays. The rest are daily services.
