Firefighters and police did a final walk-through Thursday, paying their respects at the funeral home.
Decker had a medical emergency while training last week and died. He was a 30-year veteran of the fire department.
Decker is the second Chicago firefighter to die while on-duty this year. CFD Firefighter Michael Altman was also killed two months ago while battling a fire in Rogers Park.
The funeral service will begin at 10 a.m. at St. Paul Lutheran Church, 5650 N. Canfield Ave. in Chicago. ABC7 will carry the funeral service on air and online.