"The Holy Father spoke to me in German and Italian. He was very alert. He will be working on some of the documentation that I brought to him," Cardinal Joseph Ratzinger told reporters as he left the Gemelli hospital.
The 84-year-old pope was admitted to hospital last week suffering from breathing problems and underwent an emergency procedure to create a hole in his neck to assist breathing.
Monday, Vatican officials said John Paul had been ordered not to speak, and the next update on his condition would be made Thursday.
However, Ratzinger said the pontiff conducted a business meeting Tuesday and was "very alert, both mentally and in his capacity to say essential things with his own voice."
Last month the pope spent 10 days at Gemelli being treated for flu and breathing difficulties and was re-admitted to his private 10th-floor suite last week.