The results of an experimental study of the H-3(+) and D-3(+) ions recombination with electrons in afterglow plasmas in the temperature range 50-230 K are presented. A flowing afterglow apparatus equipped with a Langmuir probe was used to measure the evolution of the electron number density in the decaying plasma. The obtained values of the binary recombination rate coefficient are alpha(binH3+) = (6.0 +/- 1.8) x 10(-8)(300/T)(0.36 +/- 0.09) cm(3) s(-1) for H-3(+) ions in the temperature range 80-300 K and alpha(binD3+) = (3.5 +/- 1.1) X 10(-8)(300/T)(0.73 +/- 0.09) cm(3) s(-1) for D-3(+) ions in the temperature range 50-300 K. This is the first measurement of the binary recombination rate coefficient of H-3(+) and D-3(+) ions in a plasma experiment down to 50 K.