The ICC confirmed in a statement that du Plessis, who led the Proteas to a Test series win in Australia recently, had been charged for breaching Article 2.2.9 of the ICC Code of Conduct, which relates to "changing the condition of the ball".
"South Africa captain Faf du Plessis has been charged for breaching Article 2.2.9 of the ICC Code of Conduct after television footage appeared to show him applying an artificial substance to the ball during the fourth day's play in the second Test in Hobart, which concluded on Tuesday," the ICC said in a statement.
Du Plessis has pleaded not guilty to the charge and, as such, the matter will now be heard by Andy Pycroft of the Emirates Elite Panel of ICC Match Referees.
The alleged incident happened on Tuesday morning when TV footage appeared to show du Plessis applying saliva and residue from a mint or sweet, an artificial substance, to the ball in an attempt to change its condition.
All level 2 breaches carry an imposition of a fine between 50 per cent to 100 per cent of the applicable match fee and/or up to two suspension points, and three or four demerit points. Two suspension points equates to one Test match.