E E "Doc" Smiths Lensmen series (published between 1934 and 1948) included fictional profanity, at least in passing.
There's a scene where someone is transcribing a conversation in an alien tongue where one of the parties blanches at the use of an insult, the strongest in the language.
In english it was something like "Shronizfied" with the meaning "descended from countless generations of muck living flatworm" .
I'll dig the books out of storage and see if I can find an exact quote.
[
Nice to have a reason to re-read a classic ...
;-) ]
scifi.stackexchange.com/users/113/Bevan
Anthony Burgess' "
A Clockwork Orange" was written in 1962, and contained an entire lexicon of "Nadsat" slang.
Some of those words are clearly intended as profanities.
Aldus Huxley's "Brave New World" predates that by quite a bit (1931), but I'd say its debatable whether the terminology in there really equates to profanity ("Gamma minus", a designation from the novel's caste system, is probably the closest thing to a profanity, although "soma", the name given to a fictional drug, is probably the most clearly "made-up" word).
There may very well be other examples, but these are the ones I could think of.
While I think it's a great question, I'm not sure we'll get a real, definitive answer.
scifi.stackexchange.com/users/1359/Beofett
In Foundation and Empire (1952) Asimov use the word Galaxy as an obscenity, often emphasizing the middle syllable (gal-LAX-y).
While not a fictional word, it is a fictional obscenity.
scifi.stackexchange.com/users/1383/Sam
Larry Niven was using the term "TANJ" in the Known Space universe in the mid to late 60's.
TANJ ->
There Aint no Justice
I'm sure there are works prior to that though.
scifi.stackexchange.com/users/1382/Zachary K
In Glory Road Robert Heinlein does actually discuss the use of profanity, and uses a word he considers profane.
Courtesy of Google Book Search
scifi.stackexchange.com/users/1399/Robusto
Mork and Mindy had Shazbott that's 1978.
Probably not the oldest but definitely an example of it.
scifi.stackexchange.com/users/1003/Omar Kooheji
In "I Will Fear No Evil" Heinlein used the word "kark" as an expletive.
Now a Google search reveals that it is all over the Star Wars universe.
What gives?
scifi.stackexchange.com/users/60981/S.DeHaven
In Triplanetary, Ralph Kinnison describes an incompetent official (to his face) as lacking "the brains that God gave bastard geese in Ireland".
One of the more original bits of invective.
scifi.stackexchange.com/users/92445/Mike Stone
There's a tradition of sorts in sci-fi where aliens or future humans use profanity that doesn't exist in the real world.  I'm curious when this started.  Which story or novel is the first time the writer made up profanity?  It's acceptable if they used real profanity in addition to their made up profanity.
What's the first instance of fictional profanity in sci-fi?
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scifi.stackexchange.com/questions/2701
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 E E "Doc" Smith's "Lensmen" series (published between 1934 and 1948) included fictional profanity. "A Clockwork Orange" was written in 1962, and contained an entire lexicon of "Nadsat" slang.   In "Foundation and Empire" (1952), Asimov used the word Galaxy as an obscenity, often emphasizing the middle syllable (gal-LAX-y). "Mork and Mindy" used "Shazbott" in 1978. Finally, in "I Will Fear No Evil", Heinlein used the word "kark" as an expletive.   Many books vie for the prize of first made up profanity including "Clockwork Orange", "I will Fear NO Evil" and "Triplanetary". It seems the oldest is the Lensmen series published in 1934 and 1948. 
Many books vie for the prize of first made up profanity including "Clockwork Orange", "I will Fear NO Evil" and "Triplanetary". It seems the oldest is the Lensmen series published in 1934 and 1948. 