The visitors did not have the easiest task coming to Stadio Angelo Massimino, and were treated to a sucker punch as they fell to the home team after taking the lead
Esteban Cambiasso scored for the visitors in the first half, but Vincenzo Montella's men turned the tables with a three-minute double salvo from Sergio Almiron and Francesco Lodi after the break to stun the Nerazzurri.
The game got off to a thrilling start as the visitors took the lead in the fifth minute after a brilliant cross by Maicon was diverted into the net by Cambiasso, who finished on the volley from the left side of the box with his left foot.
Catania found its feet later on however, and soon began pressing Inter in its own half. Almiron had a shot fly over the bar from outside the box, while Alejandro Gomez was causing the Nerazzurri's defense all kinds of trouble down the right wing.
Nicolas Spolli had a header from the center of the box fly wide of the left post soon after the half-hour mark, but the hosts were still struggling to create chances in front of Luca Castellazzi.
That changed as soon as the second half began as a quick break saw Gonzalo Bergessio square to Almiron, who sent an unstoppable shot into the top right corner to level the proceedings.
Inter received yet another blow in the 50th minute, when the ex-Saint-Etienne striker broke free of the Nerazzurri's defence and left Castellazzi with nothing to do but bring him down in the box.
Lodi converted the penalty for Catania, leaving Claudio Ranieri wondering how his team collapsed so easily in a matter of moments. The ex-Roma man threw everything forward in search of an equalizer, but his players were struggling to break the hosts' resolute defense.
The introduction of Mauro Zarate and Ricardo Alvarez hardly changed anything for the visitors, who looked short of ideas up front. In fact, Catania nearly doubled its lead in the 75th minute, when substitute Gennaro Delvecchio was denied by Castellazzi in a one-on-one.
Inter had its goalkeeper to thank moments later, when Andrea Catellani broke free on the left, but failed to put the ball past the Nerazzurri's No. 12. Claudio Ranieri's men gave everything they had in the final minutes of the game, but were ultimately unable to score.
Following tonight's result, Catania is sixth in the standings with nine points, while Inter is 17th, just above the relegation spots. Catania's next game is away to Fiorentina in a week, while the Nerazzurri hosts Chievo a day later.