Centre Elen Evans scored the only try of the game as Wales Women began their 2013 Six Nations build-up with a win over their Spanish counterparts.
Fly-half Elinor Snowsill added the conversion to the 38th-minute try at the Welsh National Centre of Excellence.
Wales head coach Rhys Edwards introduced some fresh faces ahead of the Six Nations in the uncapped game.
Props Megan York and Bethan Howell appeared alongside wing Rafique Taylor.
Wales Women kick off their Six Nations challenge against Ireland at Aberavon's Talbot Athletic Ground on Sunday, 3 February (13:30 GMT).