"The president will today be in the monastery Decani and spend Good Friday with monks and believers there," the source, who requested anonymity, told AFP.
The Serbian Orthodox Church and its followers are celebrating Good Friday ahead Orthodox Easter on Sunday, under the Julian calendar.
The visit will be Tadic's first there since the ethnic Albanian majority unilaterally proclaimed Kosovo's independence from Serbia in February 2008, despite fierce opposition from Belgrade.
Source: FOCUS Information Agency