Barroso's appointment to a top job with Goldman Sachs has stirred a lot of criticism, with demands that his EU pension should be withheld.
Reacting to the news, Corporate Europe Observatory's transparency campaigner Vicky Cann said the referral was a "welcome first step but it is two months too late."
She added, "The Commission has been forced onto the back foot by public opinion and notable interventions by the EU ombudsman, MEPs and institution staff themselves.
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"The Commission really needs to up its game on this and other revolving door cases. And a revamp of the rules for exiting commissioners must quickly follow.
"But the Barroso case is not a one-off. It is also essential that the cases of Karel De Gucht and Neelie Kroes are referred to the ethics committee, looking to see all three former Commissioners' EU pension entitlements removed at the Court of Justice."
Barroso, in a letter to Commission President Jean-Claude Juncker excerpted in the Financial Times on Tuesday, pointed out that many previous European Commissioners have taken private sector jobs. He and Goldman Sachs insist they have acted legally and with high ethical standards.
The former Portuguese Prime Minister, who stepped down after a decade as Commission President two years ago, was appointed non-executive chairman of Goldman Sachs' international arm in London two weeks after the Brexit referendum stunned Brussels.
Juncker himself had made clear in July that he disapproved of Barroso's move. "I would not have done it," he said.
The Alliance for Lobbying Transparency and Ethics Regulation (ALTER-EU) said it welcomes the news that Barroso's move to become chairman of Goldman Sachs International will be referred to the Commission's own ethnics committee.
A spokesperson said, "The Commission has finally listened to the growing voices of concern which have gained momentum over the summer.
"However, this must be the beginning of a much longer process which continues with the referral of the Barroso case to the Court of Justice.
"This is the grounds that the role breaches the EU treaty duty to act with 'integrity and discretion' - and which culminates in an overhaul of the Code of Conduct for Commissioners, so that there are tougher revolving door rules for departing commissioners alongside transparent and independent decision-making in these matters in the future."