Abstract: A hand-held digital readout thermometer measures temperatures over the range -50.degree. C. to +1100.degree. C. with a maximum error less than 3.degree. C. in that range. The thermometer includes a thermocouple, a temperature stable and temperature independent power supply, a temperature stable differential first amplifier, a second amplifier that compensates for the nonlinear response of thermocouple voltage to temperature, and an analog/digital converter controlling a digital display indicating temperature according to a preselected scale. A particular feature of the invention is a latching comparator capable of activating a low battery indicator when the supply voltage drops below a preselected value.