These coins circulated before Portugal adopted the euro. They are made of copper-nickel. On a face can be seen Portuguese shield separating the date and on the reverse a sailboat, water, and fish.
These coins are worth face value in circulated condition, and a few US dollars in uncirculated. Some dates are available only in sets that were sold to collectors, and these special dates can reach as high as $15 US dollars catalog value, as follows:
1990, 1992, 1993, 1994, 1995: $15 fully uncirculated
1996 and 1997: $8 fully uncirculated
If your coin is not one of these special dates, it is worth face value.