After team-mate Valtteri Bottas topped the time charts in opening practice, the all-conquering Mercedes cars traded positions later in the day at Monza.
Hamilton finished 0.262 seconds clear of Bottas, with Lando Norris third in his McLaren, nine tenths off the pace.
For Ferrari, it was another sobering day, this time at their home event. Charles Leclerc ended the running in ninth, three places ahead of Sebastian Vettel in the sister car.
As Ferrari’s troubles show few signs of easing, Hamilton’s quest for a seventh world championship grows stronger with each passing round.
Ahead of the eighth of 17 races here on Sunday, Hamilton holds a 47-point title lead as he goes in search of Michael Schumacher’s championship record.
Schumacher’s win tally looks set to fall soon, with Hamilton on course to move to within just one of the German’s all-time total with a 90th career triumph on Sunday.
The Mercedes cars were again in a league of their own on Friday. Hamilton’s closest championship challenger Max Verstappen, who crashed in opening practice, was back in fifth, more than a second off the pace.
Ferrari might be pleased their home race is being played out against the backdrop of scores of empty grandstands.
Leclerc and Vettel both fell off the road during second practice, with the former venting his frustration over the radio. “This car is so hard to drive,” he complained.
The 22-year-old Monegasque finished 1.4 sec slower than Hamilton with Vettel 1.6 sec down.
The Alpha Tauri pair Pierre Gasly and Daniil Kvyat finished fourth and seventh. Carlos Sainz was sixth for McLaren.
George Russell handed the keys over to Williams’ reserve driver Roy Nissany for the morning session. The Briton returned later in the day but finished last of the 20 competitors.
