Workers at the British low-cost airline, who also seek better working conditions, are planning to walk out between April 1-3.
"Due to the economic climate, easyJet workers have lost purchasing power over the last three years," SNPVAC said in a statement. "The increase in the cost of living suffocates workers and jeopardises the well-being and comfort of their families."
It also pointed out that easyJet's Portuguese bases and routes are among the most profitable, and that in other countries where profitability is lower, employees had had "significant increases".
The union did not specify the size of the increases it was seeking. EasyJet did not immediately reply to a Reuters request for comment.
Portuguese inflation slowed to 8.2% year-on-year in February from the previous month's 8.4%, but core inflation accelerated, stoked by prices of unprocessed food products.
EasyJet has 19 Portugal-based aircraft and more than 800 local employees.
(Reporting by Patricia Vicente Rua; Editing by Andrei Khalip and Jan Harvey)