Dear [Mr. Smith]:
It would give [me/us] great pleasure to have your presence at a reception in honor of the Chinese delegation.
The reception will be held in the [the City Hall], on [Tuesday, October the fourth]. Cocktails will be served promptly at [six] to be followed b dinner at [eight].
[I/We] sincerely hope you can attend. Let [me/us] know.
Sincerely yours