The first flight of a Type XI was made on 23 January 1909 on the power of a 21.5kW REP engine driving an inefficient four-blade propeller. During April and May the aircraft was refined and fitted with a 16.4-18.6kW Anzani 3 engine and Chauviere two-blade propeller. The central fin that had been fitted was removed and the rudder was enlarged and deepened, and the 'elevons' at the ends of the tailplane were arranged to function solely as elevators.

The most famous exploit of a Type XI was the cross-Channel flight on 25 July 1909. The actual aircraft used is preserved in the Paris Conservatoire des Arts et Metiers. However many Type XI were built for civil and military use: one became the first aeroplane to be used in a war, when Capitano Piazza of Italy made a reconnaissance sortie over Turkish troops at Azizia on 22 October 1911. Similarly the first bombs to be dropped from an aeroplane were released from a Type XI on 1 November 1911.