AbstractThermometric titrations of lanthanum perchlorate, titanium (III)‐chloride, uranium (IV)‐sulfate, and uranyl sulfate with EDTA solutions were carried out by using a Keithley nanovoltmeter with a rhodium‐platinum thermocouple at 25°±0.01°. The formation of LaY−, TiY−, U(IV)Y and UO2HY−ions was confirmed. The heat of reaction for the system, Ti(III)+H2Y2−= TiY−+2H+, was given byδH1= 1.933‐1.422×10m+2.056×104m(in cal) and the limiting value was evaluated to beδH