The 44 posts are both paid and unpaid and, it is believed, may include former EU Commissioners such as Michel Barnier and Mario Monti.
A special adviser is someone who because of his/her special qualifications and "notwithstanding gainful employment" in some other capacity, is employed to assist one of the institutions.
As well as former EU Commissioners, they might include ex EU or member state officials who have "high-level experience."
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The Commission has to inform the Council and Parliament, the two other main EU institutions, but neither has the right to veto any appointments.
The 12-month mandate of the current team of advisers ended Thursday and the new appointments are due to start on April 1.
Critics, however, say that the move represents a waste of public funds and two NGOs say that in one previous case, that of former German politician Edmund Stoiber, the executive broke its own transparency and ethics obligations.
The two NGOs are Friends of the Earth Europe and Corporate Observatory Europe.
The Stoiber case is the subject of an investigation by Strasbourg-based EU Ombudsman Emily O'Reilly following a complaint by the two Brussels-based non-governmental organisations.
Friends of the Earth Europe and Corporate Europe Observatory allege that the past appointment of Stoiber, a former Minister-President of Bavaria, flouted the Commission's own conflict-of-interest rules.
They pointed out that Stoiber, since he retired from domestic politics in 2007, worked as a lawyer and held paid and unpaid positions on several corporate boards in Germany.
Stoiber had previously worked as a special adviser to ex Commission President José Manuel Barroso on the high level group on administrative burdens.
The UK Independence Party has criticised the whole system of appointing special advisers and a UKIP source told this website, "This looks like an establishment stitch up, closing ranks and wasting a fortune at the same time."
Further comment came from UKIP's deputy leader Paul Nuttall who said, "The Commission already have hordes of over-paid bureaucrats at their disposal yet see fit to add 44 more so called 'special advisors' for the next 12 months, no doubt at huge cost."
"A majority of Brits already view the EU as an over-inflated and bureaucratic mess, luckily on June 23 we can say goodbye to this shameless cronyism once and for all."
A Commission source pointed out that advisers are required to sign a "solemn declaration of no conflict of interest" between their duties as an adviser to the Commission and other activities.
"The added value of appointing special advisers to the Commission derives from their exceptional qualifications and/or the relevance, quality and level of the professional experience and expertise," said the source.
Paid special advisers are usually external experts whose views are sought on matters covered by various policies and who provide skills which Commission departments do not normally possess.
Unpaid special advisers are normally former Commission officials.