Hi,
This statement was made up by Beatrice Hall, in her 1907 book Friends of Voltaire writing under the pseudonym S. G. Tallentyre.

Voltaire probably never said these exact words. They were written in 1906 by Evelyn Beatrice Hall (pseud. S. G. Tallentyre) in the biography "The Friends of Voltaire". The author did not attribute the words to Voltaire, but used them to sum up Voltaire's attitude:

" 'I disapprove of what you say, but I will defend to the death your right to say it,' was his attitude now. "

Here is the Full quote that I found on quotedetails.com :

The men who had hated book, and had not particularly loved Helvétius, flocked round him now. Voltaire forgave him all injuries, intentional or unintentional. 'What a fuss about an omelette!' he had exclaimed when he heard of the burning. How abominably unjust to persecute a man for such an airy trifle as that! 'I disapprove of what you say, but I will defend to the death your right to say it,' was his attitude now.

Voltaire made that amazing statement which is a foundation of Democracy.

Trumansdad
This is my story and I'm sticking to it....

Beatrice Hall

I disapprove of what you say, but I will defend to the death your right to say it.
-- The Friends of Voltaire, 1906

The phrase "I disapprove of what you say, but I will defend to the death your right to say it" is widely attributed to Voltaire, but cannot be found in his writings. With good reason. The phrase was invented by a later author as an epitome of his attitude. It appeared in The Friends of Voltaire (1906), written by Evelyn Beatrice Hall under the pseudonym Stephen G. Tallentyre. ...

Hall wrote:

--The men who had hated, and had not particularly loved Helvétius, flocked round him now. Voltaire forgave him all injuries, intentional or unintentional. 'What a fuss about an omelette!' he had exclaimed when he heard of the burning. How abominably unjust to persecute a man for such an airy trifle as that! 'I disapprove of what you say, but I will defend to the death your right to say it,' was his attitude now.

Hall herself claimed later that she had been paraphrasing Voltaire's words in his Essay on Tolerance: "Think for yourselves and let others enjoy the privilege to do so too."

I may disagree with what you say, but I will defend to the death your right to mis-attribute this quote to Voltaire.
-- Avram Grumer, rec.arts.sf.written, May 2000

This is a quote by an English writer from the 1800's named Evelyn Beatrice Hall who was best known for a biography she wrote about Voltaire named "The Friends of Voltaire". She coined the famous phrase although it is commonly misattributed to Voltaire himself. Hall's quote is often cited to describe Voltaire's beliefs about the principle of the freedom of speech.

Evelyn Beatrice Hall. This is an interesting question because almost everyone gets it wrong, and a quick google may also put you on the wrong track. The quote is frequently attributed to Voltaire, but it was only in a book Hall wrote about Voltaire.

It, or a variation of the phrase, is attributed to Voltaire, but probably came from Evelyn Beatrice Hall, paraphrasing an essay of Voltaire's.

http://www.classroomtools.com/voltaire.htm
http://www.brainyquote.com/quotes/authors/e/evelyn_beatrice_hall.html
http://en.wikiquote.org/wiki/Evelyn_Beatrice_Hall