A method for synchronising nodes within a sensor network, the network comprising a first node called a reference node ( A r), provided with a reference clock, and a set of second nodes ( A i) distinct from the reference node, each second node being provided with a local clock, said synchronisation being performed upon the occurrence of a given event, observed both by the reference node and the second nodes, comprising the following steps: (a) upon observing said event, said reference node broadcasts a synchronisation message after having time stamped it when emitted by means of the reference clock to provide a first time stamping value t r sync; and for each second node: (b) the synchronisation message is received by said second node and time stamped by the local clock of the same when received to provide a second time stamping value t i sync; said method being characterised in that: (c) said second node responds to the synchronisation message received by transmitting to the reference node a response message time stamped by its local clock when emitted, to provide a third time stamping value t i rep; (d) the response message of the second node is received by the reference node and time stamped by the reference clock when received to provide a fourth time stamping value t i, r rep; (e) the time t i, r evt at which the second node has observed said event, measured by means of the reference clock, from the first time stamping value, the second, third and fourth time stamping values associated with the second node, and from the time t i evt at which the second node has observed said event, measured by means of its local clock, is estimated. (a) upon observing said event, said reference node broadcasts a synchronisation message after having time stamped it when emitted by means of the reference clock to provide a first time stamping value t r sync; (b) the synchronisation message is received by said second node and time stamped by the local clock of the same when received to provide a second time stamping value t i sync; said method being characterised in that: (c) said second node responds to the synchronisation message received by transmitting to the reference node a response message time stamped by its local clock when emitted, to provide a third time stamping value t i rep; (d) the response message of the second node is received by the reference node and time stamped by the reference clock when received to provide a fourth time stamping value t i, r rep; (e) the time t i, r evt at which the second node has observed said event, measured by means of the reference clock, from the first time stamping value, the second, third and fourth time stamping values associated with the second node, and from the time t i evt at which the second node has observed said event, measured by means of its local clock, is estimated. (c) said second node responds to the synchronisation message received by transmitting to the reference node a response message time stamped by its local clock when emitted, to provide a third time stamping value t i rep; (d) the response message of the second node is received by the reference node and time stamped by the reference clock when received to provide a fourth time stamping value t i, r rep; (e) the time t i, r evt at which the second node has observed said event, measured by means of the reference clock, from the first time stamping value, the second, third and fourth time stamping values associated with the second node, and from the time t i evt at which the second node has observed said event, measured by means of its local clock, is estimated.