We consider the ARH(1) model defined by X-t = rho(Xt-1) + epsilon(t), where
rho is a linear operator on a Hilbert space; X-t and epsilon(t) are Hilber
t space valued random variables ((epsilon(t))(t is an element of N) is a wh
ite noise). We derive a central limit theor-ern for an estimator of the aut
ocorrelation operator rho based an the empirical covariance operators of th
e process and on the projection of the data on a subspace whose dimension i
ncreases with the number of observations. (C) 1999 Academie des sciences/Ed
itions scientifiques et medicales Elsevier SAS.