The actress told The Times that she had wanted to work with Almodóvar ever since she saw his 1990 movie Tie Me Up, Tie Me Down.
Cruz said: "He is so special. He has a box of surprises. You can see it in his work, but he is like that every day - you never know what he is capable of saying.
"He could have changed a whole scene the night before and blow you away with an amazing idea. He's always creating. He doesn't stop himself. He is not afraid of judgement, yet doesn't judge his characters. He's very inspiring."
She added: "He can produce his own movies. He says, 'I'm an artisan', and it's true. He has thousands of meetings with every department in the movie.
"His eye is amazing. He chooses everything in the frame. I never want to disappoint him. That would make me feel really sad."
Cruz has starred in Almodóvar's Live Flesh, All About My Mother, Volver and upcoming movie Broken Embraces.