Deadman rejected penalty claims from both sides and ruled a Ricardo Fuller goal offside to leave Powell frustrated.
The Addicks were 2-0 up with just 17 minutes on the clock after Bradley Pritchard scored the opener and Rhys Williams put through his own net.
Boro battled back after the break with Marvin Emnes and Scott McDonald on target in the final 15 minutes of the game to secure a point but it was Deadman who was the object of Powell's post-match comments.
"It is exasperating. For me the officials have got some big decisions wrong today and that is disappointing and frustrating," he said.
"There was what looked like a clear-cut penalty in the first half and another in the second - and if you ask Tony he will tell you that Middlesbrough might have had one as well.
"That said, I was pleased with the performance if not the result.
"We started off very well and were in a good place and maybe we let it drift a little and that left me a bit frustrated.
"It was a real shame we couldn't convert some of the really good chances we had."
The result means Charlton cannot be promoted, despite a late surge of form, to leave Powell proud of how they have played in their first season back in the Championship following promotion.
"I'm pleased with the way the team have performed after coming up a league," added Powell.
"It is a credit to the group and bodes well for next season."