The Tigers had already slumped to a goalless draw against Sheffield Wednesday at the Estadio Municipal de Albufeira, and stuttered once more against the Primeira Liga outfit
The hosts had the best chances of the match and Steve Bruce's side needed goalkeeper Eldin Jakupovic to keep them in the game.
New loan signing Danny Graham lined up in attack with South African trialist Daylon Claasen starting in midfield alongside George Boyd, Ahmed Elmohamady and David Meyler.
Jakupovic made two good saves in the first half as Braga tested the tourists from set-pieces, but he needed the help of Paul McShane to clear an early corner that looked destined for the back of the net.
Hull were struggling to create any clear-cut chances, with Graham and Matt Fryatt linking up nicely only to fail when the chance came to fashion an opening.
The second half was a more open affair but again Bruce's side needed Jakupovic to be at his best, as he made a string of fine saves to keep them level.