Kevin Small, 46, of Philadelphia, is in police custody. He faces charges of criminal homicide, arson and numerous other offenses.
He was denied bail during his arraignment Sunday afternoon in the death of 46-year-old Melissa Bacon-Smith, also of Philadelphia.
Investigators said the fire at The Lincoln Motel in the 2200 block of Lincoln Highway around 2:30 a.m. was the result of a domestic dispute.
Authorities said Small bought a cup of gasoline from the Wawa across the street, came back to the motel, flung it on Bacon-Smith while she was smoking and left.
PHOTOS: Fatal Bensalem motel fire
Firefighters arrived to find heavy black smoke coming from rooms 103 and 104, but firefighters had the blaze under control by 3 a.m.
Crews rescued at least three people from rooms on the second floor. Several people were taken to Aria Health Torresdale for smoke inhalation.
Police said their injures do not appear to be life-threatening. ABC7 sister station WPVI-TV spoke with witnesses who said the smoke was very intense in the hallway as they were trying to make their way out.
The Southeastern Pennsylvania Red Cross assisted people who were staying at The Lincoln.