The incident took place Wednesday at the Petraki Monastery in Athens, the capital of Greece, during a meeting of high-ranking bishops.
The 37-year-old priest, who was on trial for alleged drug offenses, was arrested unharmed and taken for questioning.
Police identified the victims as Metropolitan Bishops Antonios of Glyfada, Kyrillos of Kifissia, Kallinikos of Arta, Nikodimos of Kassandra, Dionysios IV of Zakynthos, Dimitrios of Goumenissis and Andreas of Dryinoupolis.
A policeman who helped subdue the suspect was also injured, as was a lawyer and a presiding clergyman.
Police said the liquid used was not immediately clear, but added the victims were being treated for burns.
“I express my horror for this unprecedented event,” Greek President Katerina Sakellaropoulou wrote in a tweet after contacting Archbishop Ieronymos, the head of the Greek church.
Health Minister Vassilis Kikilias visited a hospital in Athens where bishops were initially treated, joined by Archbishop Ieronymos.
Kikilias said four of the bishops were slightly injured and were receiving first aid. One was transferred to the plastic surgery unit of another hospital and the other two could also be transferred to other hospitals with specialized units, including one with a specialized eye clinic.
He said Prime Minister Kyriakos Mitsotakis had asked for constant updates on the case.
Ieronymos told reporters he was “deeply saddened” by the attack, but relieved that none of the injuries were considered by doctors to be life threatening.
The motives for the attack were not immediately clear. Public television ERT reported that the appeal hearing was held to dismiss the priest from the clergy.