When travelling on such short distances, you can take into account also busses and carpooling options: with some luck you will find very cheap options, even if you book on short notice.
What are the departure and arrival stations in Santarém and Lisbon?
Trains leave Santarém from Santarem and arrive at Lisboa - Oriente, Lisboa - Sete Rios, Lisboa - Santa Apolonia, Lisboa - Cais Do Sodre, Alcantara-Mar, Alcantara-Terra, Lisboa - Entrecampos or Lisboa - Rossio.
When are the frist and last trains from Santarém to Lisbon scheduled?
On average, it takes 1 hour to get to Lisbon by train, but you will need 57 minutes with the fastest trains. The first one is available at 04:10, whereas the last one leaves Santarém at 23:07.