Na tripolyphosphate (1) was produced by calcination of a wetted com. mixt. of NaH(2)PO(4) and Na(2)HPO(4) at 400 and 550 degrees C. Two cryst. I phases were identified by X-ray diffraction and characterized by sieve anal. Both I phases contained a lot (43-45%) of high-d. dust fraction (below 0.25 mm). The bulk d. of I after granulation was 0.848-0.871 kg/dm(3).