Fourth in the championship standings but 60 points behind Ferrari’s leader Sebastian Vettel at the mid-point in the season, the Perth driver clocked a best time of one minute 18.486 seconds.
Ferrari’s Kimi Raikkonen was second fastest, 0.234 slower on the same super-soft tyres, at a circuit that ranks almost as a home venue for the Finn.
Mercedes’ Lewis Hamilton, a point behind Vettel in the standings and chasing a record sixth Hungarian victory on Sunday, made it three teams in the top three with a lap 0.372 off Ricciardo’s pace.
Vettel was more than a second slower than Ricciardo in sixth place on a warm but cloudy morning at the Hungaroring outside Budapest.
“Struggling a lot with oversteer and rear tyres didn’t seem to be ready,” the German said over the team radio.
Daniel Ricciardo of Australia and Red Bull Racing prepares to drive during practice for the Formula One Grand Prix of Hungary at Hungaroring.Eurosport
Ricciardo’s Dutch team mate Max Verstappen was fourth with Mercedes’ Valtteri Bottas fifth.
Red Bull have brought important aerodynamic updates to Hungary, a track that has suited them in the past, and are hoping to be closer to Ferrari and champions Mercedes.
“It’s all aero stuff, but hopefully it all works together and gives us the laptime we desire. It’s a combination of things,” Ricciardo, winner in Hungary in 2014, had told reporters on Thursday.
“On the windtunnel it looks like it should help downforce and hopefully that gives us the lap time.”
There were encouraging signs at struggling former champions McLaren, who had Fernando Alonso seventh and Belgian team mate Stoffel Vandoorne eighth at the slowest permanent track on the calendar.
Renault’s luckless Briton Jolyon Palmer brought out red flags at the end of the session when he smashed his front wing on a kerb,…