Investigators were called to a house on 21st street near Q street just after 6 pm Tuesday.
Merced police and the bomb squad served a search warrant there and inside, they found improvised explosives and other evidence of illegal activity.
Investigators have not released any other details on the discovery but do say there is no active threat to residents in the area.
A 52-year-old suspect is now in custody in connection to the explosives.