Christopher Burton Phillips, 42, was arrested in Ottawa on Wednesday and returned to Halifax on Thursday.
On Friday, he will answer charges of uttering threats and possessing a weapon for a dangerous purpose.
Police allege in sworn information that Phillips threatened a police officer and possessed osmium tetroxide, a highly toxic chemical.
Phillips was arrested by Ottawa police on suspicion of carrying two dangerous chemicals from Nova Scotia to Ottawa.
Police had been tipped off by the man's wife that he was on his way to the capital. A search by police did not turn up any chemicals in his hotel room or vehicle.