Lukaku has spent the last three weeks on the sidelines with an ankle injury, and he would be fit for this weekend but he is ineligible to face his parent club Chelsea on Saturday.
"Romelu Lukaku is fully fit now and it's just a matter of making sure that we get him back to his level of match fitness that he needs," Martinez said of his loan star.
"From a medical point of view, he's fit.
"It helps in a way that he's not available for this weekend because this game may have been a little bit too early for him to be involved with the team.
"But now we've got nearly two weeks to make sure that he's fully fit for the next home game and that's very much a realistic target."
Martinez did confirm that striker Steven Naismith would be fit to play despite suffering a concussion in the win over Swansea at the weekend.
Martinez said: "Stevie has reacted really well. It was a little bit of a concern straight away when he had that delayed concussion. Two hours after the game he was fine but for the next 24 hours it's then important you're in observation and we're checking all the signs are right.
"We've done that and Stevie is perfectly well. Over the next three or four days we're going to keep an eye on how he is recovering, but I would say that Stevie will be fully fit for the weekend because he's ready now to get back to work as normal."
With Lukaku not available, Naismith could be competing with loanee Lacina Traore for a starting role after he scored on his debut against Swansea on Sunday.
"Lacina was really happy and really excited, as you can imagine. We had to make sure he was fine before we played him and he had to work really, really hard to make sure he was able to cope with the demands of the British game," said the Toffees chief.
"I couldn't be happier with his role against Swansea. The objective was to be able to do 45 minutes, and 60 minutes was at the very top of our expectations. He coped with that very well physically and you could see the threat that he carries."