TEAN-LOUIS LUCHE A French poet of this eentury, Pierre Mae Orlan, wrote "Adventure does not exist, it is only in the mind of he who is pursuing it, and, as soon as it is at one's finger tips, it vanishes to come back to life, far away, in a different shape, at the frontiers of imagination". This sentence could be used to define the adventure that many sonochemists experienced. Most of them did not even suspect that the "laboratory trick" they were using was the first contact with a considerable amount of science. If a personal note is allowed here, it ean be interesting to mention the part played by chance in my involvement in sonochemistry. Almost 20 years ago, we had to perform an apparently simple Grignard reaetion with n-butylmagnesium bromide and geranial, but the results were repeatedly unsatisfactory. The one-pot Barbier technique was attempted, also without success. From my studies at the University, I imagined that the failure of the latter reaction could be caused by a common phenomenon known by solid state chemists as passivation, which in some cases can be overcome by ultrasonication. By chance, an ultrasonie bath was sitting on the next beneh, borrowed to clean some equipment. We clamped our reluctant reaction mixture into the bath, the reaction proceeded vigorously, and ... the adventure started. Without knowing anything about cavitation, high energies, ete., we had an illustration of Goethe's word "Am Anfang war die Tat" (at the Beginning was the Act).