Portugal citizens - Ordinary passport holders are required to have visa to enter Turkey. They can obtain three month-multiple entry visas at the Turkish border gates. Diplomatic and special passport holders are exempted from visa for their travels with touristic purposes and transit to/from Turkey up to 90 days within six months, starting from the first entry date. Diplomatic and special passport holders, who are appointed to the diplomatic, consular missions or representations of international organizations accredited in Turkey, are exempted from visa for the period of their assignments.
Turkey has an online Turkish Visa Application System where you can apply for e-Visa online and pay your fees in a few minutes. Portugal citizens who meets the required criteria can obtain a visa on arrival or online at Turkish Visa Application System - https://www.evisa.gov.tr/en/apply/.