Catholic News Service reports Salesian Fr Damir Stojic thought up the scheme to keep the kids from going to other cafés after church and come together for a meal after Eucharist.
"In the Acts of the Apostles, it says the disciples used to come together for a meal after the Eucharist, so we're following a biblical ideal," Fr Stojic said.
"A lot of kids used to head for neighbouring cafes after Mass here. We came up with this scheme for persuading them to hang out at the church instead."
The Jedno (Sail) cafe opened recently in a parish hall adjoining Zagreb's Holy Spirit Church and attracts many of the students and young people attending the regular Sunday youth Mass.
"Student helpers thought up the idea of paying with prayers. We have encouraged parents to donate food and drink for the café," he said.
"Jedno could be seen as continuing a tradition since most Salesian parishes worldwide ran cafes at their churches."
Prices at Jedno vary from three Our Fathers for a standard cup of coffee to a more expensive Coca-Cola (five Hail Marys and a Glory Be), while a cappuccino costs four Our Fathers.
Other items offered include fruit drinks, teas and hot chocolate, as well as a range of cakes and biscuits.
Catholics make up 88 percent of the 4.4 million inhabitants of Croatia.
At Croatian cafe, youths pay for drinks with Our Fathers, Hail Marys (Catholic News Service 17/02/08)