Tykes winger Adam Hammill scored a stunning opening goal midway through the first half, but Hull midfielder Kevin Kilbane fired through a crowded penalty area to snatch a point for the visitors, who are without a win in six league matches.
Hull substitute Caleb Folan's second-half lob hit the crossbar, while Tigers goalkeeper Matt Duke made several superb saves to deny Barnsley, who were also refused a late penalty by referee Andy D'Urso after visiting defender Andy Dawson appeared to have hauled down Jim O'Brien.
Robins said: "We did enough to win three football matches and that's the frustrating thing. The approach play and movement off the ball was excellent.
"We created many chances. We also hit the bar and had a penalty appeal turned down.
"It was a disappointing goal to concede, but then we created several more chances before the final whistle and we should have had a penalty.
"I don't think there's any doubt that it was a penalty, but the referee didn't give it.
"Some of the stuff we're playing is fantastic, but we haven't been ruthless enough. That ultimately is what has cost us the three points."
Hull manager Nigel Pearson was pleased with the point that keeps his side out of the bottom three.
He said: "I think that as a game shows where we are at the moment.
"We were disappointed with the first-half performance, but the second half was much, much better.
"Clearly our areas to improve are psychological. We've had a losing culture for too long at the club and that has to change.
"The key was the application of the players and their desire to do something about it. You've got to move on rather than dwell on things like a player making a mistake.
"That side has the ability to perform to a better standard, but there are things that need to be altered at the club.
"I was pleased with how the players made the system work in the second half."