Antonio Cassano set the Nerazzurri on their way with his fifth goal of the season, meaning Catania are still waiting for their first win at the San Siro. The home side are now neck and neck with Lazio as the race for Champions League places hots up.
Sergio Almiron wasted a glorious chance on seven minutes after a defence-splitting ball exposed Inter's back three. The Argentinean midfielder controlled the ball with his face, then blazed over from point blank range. It was a case of the right ball finding the wrong man.
Cassano - picked ahead of Philippe Coutinho, certainly had the bit between his teeth. The enigmatic frontman got behind the Catania defence to chest down a high ball, only to be thwarted by visiting keeper Mariano Andujar, who ran out to claim.
Cassano retreated into a deeper role. His exquisite long ball found Palacio on 19 minutes. The former Genoa man had time to control, but he rushed a weak header straight at Andujar.
Cassano was threatening to do something and he finally opened the scoring on 28 minutes. Sneaking past the visiting defence once more, Cassano met Esteban Cambiasso's peach of a cross at the far post to guide a header under Andujar's legs.
Catania's 4-3-3 setup was being pushed back into a 4-5-1, as Inter continued to press.
After half an hour, Giovanni Marchese managed to fire a speculative 30 yard strike into the gloves of Samir Handanovic. On the stroke of half time, the left back sauntered forward once again, crossing for Mariano Izco to send a free header wide.
Two minutes into the second half, Almiron threaded through for Alejandro Gomez, but an offside flag came to Inter's rescue. Javier Zanetti then tried to release Diego Milito, but put too much on his pass and Andujar ran out to smother.
Catania went to sleep on a long throw in. Milito ran clear and slid an inviting ball across for Cassano, only to see Andujar smother it. Cassano tried to do the same for Palacio, but put it too far in front of him and Palacio couldn't slide onto it in time.
Andujar almost gifted Inter a second when he let a Milito shot squirm underneath his body. Fortunately for the keeper, the ball trickled wide.
The game opened up in the last 20 minutes. A Pablo Barrientos shot turned cross almost met the head of Almiron at the far post. Undeterred, Almiron fired a shot from the edge of the box, which deflected wide off Andrea Ranocchia.
Inter substitute Ricardo Alvarez turned the Catania defence inside out as he ran into the box, only to take too many touches. When he tried to bring the ball back onto his favoured left side, the visitors cleared the ball.
Gomez went down under substitute Fredy Guarin in the box and was denied a penalty.
The scare didn't put the home side off, as they were desperate for a second goal. Cambiasso crossed for Ranocchia to guide a header onto the post. Alvarez then wasted another chance, taking an extra touch instead of hitting his shot first time. Andujar saved the effort with his legs.
Palacio finally put the game beyond Catania five minutes from time. After enduring a frustrating afternoon, Palacio chested down a Milito cross and fired a volley across goal and under Andujar's body.
Inter: Handanovic, Ranocchia, Samuel, Juan Jesus, Obi, (Gargano 62) Mudingayi, (Guarin 71) Cambiasso, Zanetti, Cassano, (Alvarez 69) Milito, Palacio
Catania: Andujar, Alvarez, Legrottaglie, Spolli, Marchese, Izco, (Castro 65) Lodi, Almiron, (Ricchiuti 80) Barrientos, Bergessio, Gomez