The ex-Reds forward netted a brace in a dominant first-half display by the hosts at the boisterous Turk Telekom Arena.
First, Baros hooked a volley beyond Alexander Doni to break the deadlock on eight minutes before converting with a close-range header just before half-time.
Liverpool posed more of a threat in a much improved second-half display, though they were unable to breach the Galatasaray rearguard and Johan Elmander's late volley ensured the Turkish side claimed victory.
Kenny Dalglish named a youthful-looking squad for Liverpool's journey to Turkey, and the starting XI contained the likes of John Flanagan, Jack Robinson, Jonjo Shelvey, and Martin Kelly.
There was a more experienced feel to the attack, though, with Andy Carroll partnered by Joe Cole, while Sotirios Kyrgiakos captained the side.
New signings Charlie Adam, Stewart Downing and Jordan Henderson remained on Merseyside ahead of Monday's trip to Norway.
Meanwhile, a few familiar faces in Galatasaray's team selection, not least one of the Reds' many heroes from that epic night at the Ataturk Stadium in 2005, Baros.
The Turk Telekom Arena may have only opened in January, but it already has a place in the Guinness Book of World records for generating the loudest crowd noise at a sports stadium - and that was certainly in evidence as a wall of noise greeted the opening exchanges.
The decibel levels certainly seemed to have the desired impact upon Galatasaray, and they should have taken the lead just 30 seconds in, but Baros stabbed wide when released into space inside the area.
Moments later, Arda Turan looped a header narrowly wide of Alexander Doni's far post as the hosts looked to seize immediate control of the contest.
Gala's early pressure paid dividends on eight minutes, however, as Baros broke the deadlock against his former employers, hooking in a low right-wing cross from 12 yards to capitalise on some slack marking inside the box.
The best Liverpool could muster in response in the opening exchanges was a wayward Carroll effort from distance as the Turkish side maintained their early tempo.
As the half-hour mark loomed, Selcuk Inan's audacious chip from the edge of the box did little to trouble Doni, while at the other end Jonjo Shelvey's in swinging free-kick only just evaded both Carroll and Kyrgiakos in the centre.
Back came Galatasaray and Baros saw a powerful downward header parried away by Doni before Inan's follow up was deflected behind by Martin Kelly.
Liverpool's No.34 spurned a gilt-edged chance on 36 minutes when he turned Kyrgiakos's knockdown wide when inside the six-yard box when free, though the linesman's flag was raised for an infringement, before Doni pushed Turan's low drive around the base of the post.
And Galatasaray's lead was extended four minutes before the break when a near-post flick at a corner for the home side found Baros in space at the back post, and the Czech forward made no mistake with his close-range header.
Shelvey lofted a shot wide in first-half stoppage time, but after an opening 45 minutes dominated by the home side, the half-time whistle would provide the Reds with a chance to regroup.
Dalglish opted to introduce Dirk Kuyt and Alberto Aquilani into the equation during the interval, as well as Brad Jones, and there were signs of an improved showing in the early stages of the second period as Carroll saw a header parried by substitute Ufuk Ceylan.
The introduction of Kuyt and Aquilani helped Liverpool take the game by the scruff of the neck, and the pair combined brilliantly only to see the latter's effort thwarted by a fine save by Gala's goalkeeper.
Liverpool continued to probe, with Gala struggling to replicate the intensity of their first-half performance.
With time ticking away, Ceylan blocked another aerial attempt from Carroll but Galatasaray made sure of victory when former Bolton striker Elmander netted with a stunning volley from the edge of the box.
By: James Carroll
Source: Liverpool FC Official
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Meanwhile, Dalglish has been busy selling off spare parts, as he tries to negotiate deals for everyone from Alberto Aquilani and Raul Meireles to Jay Spearing and David Ngog. 
