  We present the low-resolution transmission spectra of the puffy hot Jupiter
HAT-P-65b (0.53 M$_\mathrm{Jup}$, 1.89 R$_\mathrm{Jup}$, $T_\mathrm{eq}=1930$
K), based on two transits observed using the OSIRIS spectrograph on the 10.4 m
Gran Telescopio CANARIAS (GTC). The transmission spectra of the two nights are
consistent, covering the wavelength range 517--938 nm and consisting of mostly
5 nm spectral bins. We perform equilibrium-chemistry spectral retrieval
analyses on the jointly fitted transmission spectrum and obtain an equilibrium
temperature of $1645^{+255}_{-244}$ K and a cloud coverage of
$36^{+23}_{-17}$%, revealing a relatively clear planetary atmosphere. Based on
free-chemistry retrieval, we report strong evidence for TiO. Additional
individual analyses in each night reveal weak-to-moderate evidence for TiO in
both nights, but moderate evidence for Na or VO only in one of the nights.
Future high-resolution Doppler spectroscopy as well as emission observations
will help confirm the presence of TiO and constrain its role in shaping the
vertical thermal structure of HAT-P-65b's atmosphere.
