A method and system are provided for detecting the wax appearance temperature (WAT) of a hydrocarbon fluid sample. The hydrocarbon fluid sample is run through a microfluidic channel at controlled temperatures while sensing the pressure drop across the channel. The WAT is determined by finding a temperature at which the pressure (drop) across the microfluidic channel caused by a temperature reduction of the hydrocarbon fluid sample does not stabilize over a given time interval, thereby establishing the WAT as being at that temperature or between that temperature and a previous higher temperature where the pressure (drop) stabilized over time.