Neither of the men or the company they worked for can be named due to suppression orders.
The company has offices in New Zealand and Australia and operates a factory.
The sacked worker was with the company for more than 31 years. According to a finding into an earlier hearing he had an "impeccable record''. He appeared to be loyal, take his role serious and act conscientiously.
The incident occurred at an awards ceremony in February when he received an award in recognition of his achievements with the company.
According to the boss, he and the employee were asked to stand together for a photo.
"Whilst standing close (the employee) took the opportunity to place his hand on and cup my left buttock,'' said the boss' evidence.
"I was understandably shocked and appalled by such a brazen act which I considered an absolute violation of my personal space and my being.''
It was further alleged that the employee had made "inappropriate comments'' at the ceremony, and prepared two acceptance speech - one appropriate and the other inappropriate.
The employee told the authority he had put his right arm around the boss's waist: "Without realising it my hand may have slipped due to the slipperiness of his suit material and as I moved away from our embrace for the photo this must have been when I possibly touched (his) bottom.
"I have no real memory of touching his bottom as I was moving apart from him to give my speech which I was focusing on and was a little nervous.''
The employee said it was initially alleged he "pinched'' the boss's backside, but this was changed to "placing (his) hand on (the boss's) backside''.
The authority decision makes numerous mention of the "cupping'' of the buttock.
The company found the man's conduct to be "inexcusable and outrageous'' and sacked him.
Its investigator said video evidence of the ceremony showed the employee's arm and hand were pointed down towards the boss' left buttock - consistent with the latter's evidence.
''(The boss) makes an awkward and nervous laugh and the photo is taken.
"As soon as the photo is taken, (the boss) puts his arm out to distance himself from (the employee).''
However, Mr Anderson found that none of these observations was "even remotely'' collaborated by the video recording.
"On the contrary, at all times he appears to be quite happy, smiling and jovial towards (the employee). He does not even show the slightest hint of being treated by (the employee) in the manner he describes.
''... His ability to disguise his feelings, if this is what he did, was little short of an Oscar-winning performance.''
Mr Anderson ordered that the employee be reinstated on a temporary basis.
