  The ALICE experiment features multiple particle identification systems. The
measurement of the identified charged hadron $p_{t}$ spectra in proton-proton
collisions at $\sqrt{s}=900$ GeV will be discussed. In the central rapidity
region ($|\eta|<0.9$) particle identification and tracking are performed using
the Inner Tracking System (ITS), which is the closest detector to the beam
axis, the Time Projection Chamber (TPC) and a dedicated time-of-flight system
(TOF). Particles are mainly identified using the energy loss signal in the ITS
and TPC. In addition, the information from TOF is used to identify hadrons at
higher momenta. Finally, the kink topology of the weak decay of charged kaons
provides an alternative method to extract the transverse momentum spectra of
charged kaons. This combination allows to track and identify charged hadrons in
the transverse momentum ($p_{t}$) range from 100 MeV/c up to 2.5 GeV/$c$.
Mesons containing strange quarks (\kos, $\phi$) and both singly and doubly
strange baryons (\lam, \lambar, and \xip + \xim) are identified by their decay
topology inside the TPC detector. Results obtained with the various
identification tools above described and a comparison with theoretical models
and previously published data will be presented.
