Brazil youth international Coutinho, 19, moves from Inter Milan on loan until the end of the season, and Nigeria international Uche, 29, signed a one-and-a-half year deal to move from Swiss side Neuchatel Xamax.
"I want to help the team get into the Champions League," Coutinho told reporters when he arrived in Barcelona.
"I want to get playing time ahead of the Olympic Games in London."
Espanyol, UEFA Cup finalists in 2007, are fifth in La Liga and only kept out of the Champions League places on goal difference by fourth-placed Levante.
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