Cadiz, who have won five of their 22 league games so far this season, are 17th with 22 points, two above Valencia and a game more in the relegation zone.
With an eye on their Europa League playoff spot at Manchester United on Thursday after a 2-2 draw in the first leg, manager Xavi Hernandez made six changes to his starting line-up, but his side showed no signs of slowing down .
It was a largely one-sided contest at the Camp Nou stadium, with Barca unwilling to relinquish control despite giving their opponents few chances to score, including two goals denied and two strikes off the post.
“Scoring twice before the break gave us a comfortable lead, which practically sealed our victory in the second half,” Xavi told Movistar Plus.