The 19-year-old is in contention for his first Premier League start when Everton take on Cardiff on Saturday, just days after he made a scoring debut in the Capital One Cup win over Stevenage.
Already impressed, Martinez says there is a possibility of extending the loan agreement into a second season.
He said in the Daily Star: "We can take him for a longer period.
"I don't think it is an option to take him permanently because the hopes in Barcelona are huge for him, but with him being such a young man, perhaps we could extend it for a further year."
Martinez, who replaced David Moyes at Goodison Park in the summer, has also confirmed that the deal is beneficial to the club in many ways.
He added: "The deal is performance based, so, depending on how many games he plays, financially there is a difference. It decreases if he plays more."
The former Wigan boss has been impressed with the Spain Under-21 international's ability to quickly adapt to the English game and believes the style of play suits the youngster.
"I agree that he could really thrive in the English game," Martinez added.
"He is an old-fashioned winger who is incredible in one-on-one situations. He is a finisher, but he needs to get used to it and change some habits."