In this paper, we study a form of stability for a general family of nondiff
usion Markov processes known in the literature as piecewise-deterministic M
arkov process (PDMP). By stability here we mean the existence of an invaria
nt probability measure for the PDMP. It is shown that the existence of such
an invariant probability measure is equivalent to the existence of a sigma
-finite invariant measure for a Markov kernel G linked to the resolvent ope
rator U of the PDMP, satisfying a boundedness condition or, equivalently, a
Radon-Nikodym derivative. Here we generalize existing results of the liter
ature [O. Costa, J. Appl. Prob., 27, (1990), pp. 60-73; M. Davis, Markov Mo
dels and Optimization, Chapman and Hall, 1993] since we do not require any
additional assumptions to establish this equivalence. Moreover, we give suf
ficient conditions to ensure the existence of such a sigma-finite measure s
atisfying the boundedness condition. They are mainly based on a modified Fo
ster-Lyapunov criterion for the case in which the Markov chain generated by
G is either recurrent or weak Feller. To emphasize the relevance of our re
sults, we study three examples and in particular, we are able to generalize
the results obtained by Costa and Davis on the capacity expansion model.