According to Sky Italia, the deal is complicated by Napoli's insistence that they get full image rights to the player – Higuain holds 50 per cent of his image rights at Real which is worth about two million euros a year to him via a sponsorship deal with Nike.
The report claims that Napoli would be willing to pay Higuain €115,000-a-week to try and tempt him to release his image rights.
Higuain has been heavily linked with Arsenal this summer but their interest has cooled as Real's valuation has increased.
The Serie A club have money to spend after agreeing the sale of Uruguay striker Edinson Cavani to Paris St Germain for a reported fee of 64 million euros (£55m) and are looking to strengthen their squad for their domestic and Champions League campaigns.
Napoli last week agreed to sign versatile Spanish forward Jose Callejon from Real having already secured the services of Belgium winger Dries Mertens.
Spain defender Raul Albiol has also signed a four-year contract after again joining from Real while Liverpool goalkeeper Pepe Reina has agreed a season-long loan and will join in the next few days.
The new signing have joined up with Spaniard Rafa Benitez, who was appointed Napoli coach at the end of May.
The former Liverpool, Chelsea and Inter Milan manager replaced Walter Mazzarri, who quit after the team finished second behind Juventus last season to qualify for Europe's elite club competition.