A retired Victorian priest is set to learn his punishment for molesting five boys decades ago, sometimes after climbing into their beds.

Peter Waters, now 74, began grooming one boy after he entered the confessional booth to reveal the Catholic sin of masturbation.

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When the boy stayed overnight with the priest during the 1980s, Waters climbed into his bed and molested him as the child pretended to sleep.

The victim's brother suffered similar abuse, waking to Waters climbing into his bed after socialising together, consuming alcohol and cigarettes.

Waters abused the brothers and three other boys across Melbourne parishes between 1974 and 1987.

One victim said Waters had "swooped in" during his teen years while his parents were divorcing.

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He described returning home from school to find his abuser smoking and drinking coffee with his mum, according to a statement read to Victoria's County Court.

The retired priest was last month found guilty by a jury of six counts of indecent assault and one count of gross indecency with a child under 16.

The day a second trial was to begin, Waters admitted to one count of indecent assault of a male and two counts of indecent assault.

He is expected to be sentenced in the County Court on Wednesday.