A series of titanium aluminophosphate molecular sieves with four different structure types including TAPO-5 (AFI topology), TAPO-11 (AEL topology), TAPO-31 (ATO topology), and TAPO-36 (ATS topology) have been studied to determine the titanium location in the aluminophosphate framework. Some Ti(IV) was reduced to paramagnetic Ti(LII) by gamma-irradiation and CO reduction to serve as a spin probe. The electron spin resonance (ESR) parameters confirm Ti(III) formation but do not clearly confirm a tetrahedral environment. However, P-31 and Al-27 electron spin-echo modulation of Ti(III) provide evidence based on phosphorus distances for titanium substitution into a tetrahedral phosphorus site of the aluminophosphate framework in all four structures. When the TAPOs are treated with NO, an NO radical is observed by ESR but Ti(III) is not formed.