Hi, first of all, let me stress that this answer is needed for a novel
I am writing and will not be put to practical use ! :-) The
protagonist needs to dissolve his victim as soon as possible (bones
can be left intact, but the flesh must be removed) before the cops
locate the body. The plot dictates that this should be done within a
week if at all possible. I was toying with lime and HCL, but then
remembered that one will neutralize the other! Can you please help?
Many thanks!

I've always used Coca Cola.

It's also great for removing rust.

John George Haigh (1949)  Told the court it took 48 hours to reduce
Mrs Durand-Deacon to "a residue composed of chemically reduced
remaines of flesh and bones".  But it did not effect her false teeth.
Mr Haige used Sulfuric Acid as used for electro-plating.

I'm not sure if the chemical breakdown is a vital part of the story,
but the best way to do it is with animals.  I saw a story on the
Discovery Channel about a Biologist at Berkeley that uses Dermestid
Beetles and maggots (from Botflies, I think) to eat away the flesh of
whale carcasses that have washed up on shore.  The adavantage being
that the beetle populations are cheap and nearly infinitely expandable
without the use of caustic chemicals.  They pick the flesh completely
clean and you don't have to worry about neutralizing and disposing of
chemicals.  For your story it would make it possible for the
protagonist to dispose of an entire body with conspicuously buying 50
gallons of hydrochloric acid, and dealing with the equipment needed to
house and use it safely.  This biologist says that he prefers using
the beetles because they don't discolor the bones in the way that
strong acids or boiling the bones would, so for your story it would be
easier to cover-up.  The beetles are used in taxidermy fairly
regularly for the same reason.  Check out this website:
http://www.skulltaxidermy.com/kits.html
   The guy in this webiste says that his beetles can pick clean a bear
skull in less than 24 hours so it is not inconceivable to clean a
human body in a week with enough beetles.

Drain cleaner.

Oh, yes, Follow Kemlo's suggestion and check out legendary British
killer, John George Haig!  I wrote & produced a mini-documentary about
him several years ago.   I just looked up some of my notes. . .

Haigh,  a k a  "The Acid Bath Murderer," while in prison on fraud
charges came up with the idea for a series of "perfect murders."  He
experimented while in prison with jam jars, field mice and very small
quantities of acid in order to work out how long it would take a body
to disappear in acid.  On his release, he then started practicing on
human beings.

Haigh dissolved 5 people between 1944 and 1948 -- then stole their
property by forging letters and documents and posing as a relative. 
All of the people he killed were his friends, including Mrs.
Durand-Deacon, the 6th and last of his victims.  He got her to come to
his "workshop" in Crawley, where he shot her in the head.

He placed her body in a 45-gallon oil drum, went out for a cup of tea
and a poached egg on toast, then returned and filled the drum with
sulfruic acid, left it to stand for 2 days until the body had
disintegrated and swilled out the residue across the yard outside.

When the police searched Haigh's workshop, they found a rubber apron,
gas mask and empty carboys of acid.  Plus letters and correspondence
and the recently fired revolver.

Haigh finally confesssed.  "I've destoryed her with acid.  You'll find
the sludge that remains at Leopold Road.  Every trace has gone," he
bragged.  "How can you charge me with murder when there is no BODY?"

A leading forensic pathologist foraged around in the soil where the
drums of acid had been dumped.  He immediately picked up a small
stone.   What Haigh didn't realize, the skilled pathologist did: 
GALLSTONES don't dissolve quickly in acid.

In the end, 475 pounds of earth were analyzed, which came to 28 pounds
of animal fat, part of a foot, two more gall stones, Mrs.
Durand-Deacon's red handbag and Mrs. Durand-Deacon's dentures.
(Try saying THAT 5 times fast.)

Haigh's trial lasted only 2 days, during which he shocked the
courtroom by calming working on a crossword puzzle.  The jury
deliberated for 17 minutes.

In 1949 Haigh was put to death by hanging.  A perfectionist to the
end, he asked for a rehearsal of his execution.  (The authorities
declined.)

There are many photographs of Haigh's workshop and the drums and gas
mask, etc., if you're interested and I also recommend an excellent
book that goes into more detail about his "technique."
"The Acid Bath Murders," by David Briffet.

Hello, everyone! And many thanks for your feedback. I actually
remember seeing that documentary on TV a couple of years ago, but I
had a very vague memory and couldn't remember the killer's name! (or,
indeed, any relevant info). This truly is excellent information! The
beetles are also very thought-provoking. In answer to a question
asked, no, the decomposition of the body does not have to happen
chemically. Basically, it's a black comedy (as you might gather!) and
one of the key scenes requires the protagonist to kill someone but
lead investigators to think it is a much older body, thereby bringing
the archaelogists to the scene (and ushering the cops away). Thanks
again to everyone who posted here :-)