After all their troubles off the field - and being forced to start the season in administration - Barnsley were delighted to grab three points on a sweltering hot day.
Watched by new owner Sean Lewis the Tykes grabbed all three points thanks to a second-half penalty from Dean Gorre.
Barnsley manager Gudjon Thordarson fielded four new players in goalkeeper Sasa Ilic, Tony Gallimore, Craig Ireland and Peter Handyside.
All four played particularly well as the home side delighted an appreciative crowd of 8,540.
Barnsley started brightly and striker Rory Fallon almost put his side in front inside the first 90 seconds.
Gallimore floated in a free-kick from the left and Fallon out jumped goalkeeper Simon Brown but his goalbound header was prevented from going in by the covering Scott Fitzgerald.
After 24 minutes Steve Hayward saw a terrific free-kick tipped over by Brown.
Colchester went close through their lively striker Craig Fagan whose curling 20-yarder hit the inside of the post.
Barnsley broke the deadlock 40 seconds into the second half.
Gallimore's cross was aimed at Fallon but the big striker was pulled back by Fitzgerald. Gorre stepped up to take the penalty and coolly sent Brown the wrong way.
Colchester were given a penalty of their own after 68 minutes when Ireland was penalised for handball, but Joe Keith blasted the spot kick well over the bar.
Justice was done and Barnsley took a deserved three points.