Let k be a field of
characteristic zero, F = k((Y )) the local field of Laurent series in a variable Y , and
∂Y the usual derivation of F. The purpose of this paper is the complete description
of k-derivations on the formal pseudo-differential operator skewfield K = F((X,∂Y)).
An application of this result is given to study the structure of higher derivations in
skewfields of characteristic zero.