We have developed a new noncontact optoacoustic method for simultaneous measurement of flow velocity and temperature in a flowing fluid to accuracies of 5 cm/s and 0.1 °C, respectively. It is applicable for pure particulate‐free gases and liquids. A pulsed ND‐doped yttrium aluminum garnet (YAG) laser of 40‐mJ energy and 10‐ns duration generates an acoustic pulse whose propagations in directions along and against the flow are monitored by a total of three cw probe beams. We also describe the minimization of errors due to a blast wave (which propagates faster than sound) being generated at the source.