However, Pep Guardiola's side may consider it a point gained rather than two lost after playing 28 minutes with 10 men after Dani Alves was sent off.
Espanyol created the best chance just before the break when Barca goalkeeper Victor Valdes tipped Osvaldo's close-range shot onto the post, while the visitors also hit the woodwork early on through Pedro Rodriguez's mishit cross.
"I have to congratulate my colleagues for the great work they had to do with one less," Alves said afterwards.
The full back said it is a decision he must accept and move on from, with Barca due to play Inter next week in the Champions League.
"The duel with Inter promises to be exciting and we will do our best to go to Milan and get a good result."