  The presence of mixed modes makes subgiants excellent targets for
asteroseismology, providing a probe for the internal structure of stars. Here
we study 36 \emph{Kepler} subgiants with solar-like oscillations and report
their oscillation mode parameters. We performed a so-called peakbagging
exercise, i.e. estimating oscillation mode frequencies, linewidths, and
amplitudes with a power spectrum model, fitted in the Bayesian framework and
sampled with a Markov Chain Monte Carlo algorithm. The uncertainties of the
mode frequencies have a median value of 0.180 $\mu$Hz. We obtained seismic
parameters from the peakbagging, analysed their correlation with stellar
parameters, and examined against scaling relations. The behaviour of seismic
parameters (e.g. $\Delta\nu$, $\nu_{\rm max}$, $\epsilon_p$) is in general
consistent with theoretical predictions. We presented the observational p--g
diagrams: $\gamma_1$--$\Delta\nu$ for early subgiants and
$\Delta\Pi_1$--$\Delta\nu$ for late subgiants, and demonstrate their capability
to estimate stellar mass. We also found a $\log g$ dependence on the linewidths
and a mass dependence on the oscillation amplitudes and the widths of
oscillation excess. This sample will be valuable constraints for modelling
stars and studying mode physics such as excitation and damping.
