Catholic Christmas Eve mass typically lasts about an hour and a half. However, this can vary depending on the specific parish and the number of attendees. It's important to plan accordingly and arrive early to ensure you don't miss any of the important parts of the service. The service usually starts with the lighting of the Advent candle and then proceeds through a series of readings, prayers, and hymns. At the end of the service, there is usually a collection and a procession of the gifts to the altar. It's a beautiful and meaningful way to celebrate the birth of Jesus Christ.