Abstract: The present invention provides an apparatus for use in indicating the boiling point of fluids across a wide temperature range which comprises a meter of the portable hand-held type including a probe for insertion vertically into a fluid for testing, with heating means in the probe for heating of the fluid, and monitoring means for monitoring the temperature rise of heated fluid for indicating the boiling point temperature of the fluid. The probe portion has an inner chamber, in which are located the heating means and temperature monitoring means, and which is provided with thermal insulation means for restricting heat loss from the inner chamber during heating up of the fluid in the inner chamber up to its boiling point.