In this paper the relationships between small-signal h-parameters and elements of the natural equivalent circuit of the common emitter configuration of junction transistors are studied. From experimental results of h-parameters of two typieal alloyed PNP transistors (one 2N104 and one п-6 transistor) the relationship of h-parameters and elements of natural equivalent circuit vs operating frequency and d. c. operating condition (d.c. emitter current and d.e. collector voltage) are evaluated. Results thus obtained ace then compared with results obtained from analysis based on calculations using physical constants of the transistor. The explanation of the behavior of the reverse open-circuit voltage amplification factor, μbc, of the common emitter circuit is given in detail. Characteristics of μbc and properties of h22 (the output admittance with input open) are correlated. This paper gives complete information about h-parameters and natural equivalent circuit of two transistors, serving as an important reference for both device men and research workers on transistor circuits.