Starting from flare models of Karličky (Solar Phys. 130, 1990, 347), we present the timedependent numerical simulations of hydrogen plasma excitation and ionization on subsecond time scales. These scales are consistent with the spiky behaviour of the kinetic temperature produced by non-thermal electron beam pulses of very short duration. Self-consistent numerical solution of
time-dependent, NLTE problem for a three-level plus continuum hydrogen atom allows us to predict theoretically the behaviour of
the Hα line intensity variations on subsecond time intervals. We present the Hα temporal profiles, evaluated at the line center and in the wing, which can be qualitatively compared with some recent flare observations obtained with very high (0.1 sec) temporal resolution. and Full version of this contribution was published in Solar Phys. 135 (1991), 65.