The decarbonization process for silicone resin particles in a hydrogen gas flow and the properties of resulting Si–O–C(–H) ceramics were investigated in terms of mass loss, specific surface areas, and photoluminescence (PL) spectra. In particular, PL spectra of Si–O–C(–H) ceramics decarbonized in a hydrogen gas flow at 800°C and 1100°C were investigated in detail using pulsed laser excitation. The powder decarbonized at 800°C (SiO1.68C0.48H1.66) exhibited short-lived PL with a peak at 410 nm that decayed within a time range of 10–60 ns. After evacuation of the system down to 1 Pa, long-lived PL decaying within a time range of 1.0–4.0 s appeared around 560 nm, in addition to the short-lived PL. On the other hand, the powder decarbonized at 1100°C (SiO1.54C0.26H0.12) exhibited yellow–white PL with a peak at 520–530 nm. Time-resolved analysis revealed that the broad emission consisted of both short-lived PL (peak at 500 nm) and long-lived PL (peak at 580 nm). This long-lived PL in the powder decarbonized at 1100°C was stable in air. Such stabilized long-lived PL was also observed in the powders decarbonized at 1000°C–1300°C.