More than 1000 visitors and staff were evacuated after reports of a fire inside Questacon on Tuesday afternoon, an emergency services spokeswoman said.
The fire forced ACT Fire and Rescue to close down the building and restrict access to some roads.
The small fire was extinguished by firefighters but people have been asked to avoid the area to allow emergency services personnel to investigate the incident.
The venue will be closed on Wednesday, and any tickets bought will be refunded.
Parkes Place West, Mall Road west were closed and the Questacon car park was also blocked for a few hours until about 5.30pm.
There were no reports of injuries, the spokeswoman said.
"Six appliances were [sent to the location] and ACT Ambulance, just as a precaution, and ACT Policing [were] also on scene," she said.
"Questacon is now closed for the day."
The spokeswoman said the firefighters found the incident was caused by an electrical fire inside one of the rooms about 2.40pm.
"The fire was contained to the room of origin, there was no spread to the rest of the building, some damage occurred," she said.
A Questacon spokeswoman said the science centre would also be closed on Wednesday and those who booked visits during this period would be compensated.
"The centre was closed for the afternoon and will remain closed tomorrow while assessments are made. All visitors with tickets for this afternoon and tomorrow will have their tickets honoured or refunds arranged," she said.
"Safety of visitors and staff at the centre is of paramount importance to Questacon."
The spokesperson said updates would be posted on the centre's social media accounts and website.
