Ferrer took under 45 minutes to clinch the opening set, but it could have been earlier as the Spaniard dominated the court to secure a five to love lead in Barcelona.
The set point took up to seven minutes to reach as the 30-year-old's fellow countryman kept denying the world number five the advantage until Ferrer forced the point home.
Montanes made more of an impact in the second, producing impressive shots during his service game. However, it didn't take long for Ferrer to take the reins and snatch a break to take the lead in the set.
The third seed continued to dominate and eased into the quarter-finals for another all-Spanish clash against Feliciano Lopez.