. Experimental study of optical and electrical properttes of sixrndifferent g r o ups of electroluminescent diodes (LEOs) was carried OtK. at..rnand near room temperatures. The first catego ry of the diodes consis t edrnof f our g r o u ps of red (LQ 1131). orange (experimental samples withoutrnCA t alogue number) yellow I (LQ 1431) and green I (LQ 1731) colored LEOsrnfa b r l catd by TESLA Elec t ronics, in Cze c hoslovaki n. Each o f t hese groupsrncons i s t ed of seven samples. tn the second ca t egor y , t he re were t wo groupsrno f ye llow n (LED4 586- 481) and green 11 (LED4 586- 491) c o lored LEOs eachrnwith three samples. These second category LEDs were fab ric a ted by Ra d J 0rnSpares (RS) of England.rnComparative studies of I-V. C-V. lphoto -v. e~is8ion spect r a a ndrnband gap were carried out for all these diodes. The i -V characte r is ticsrnrevealed that the ideality fector 'n' In [~ eqV / nKT range, from 1.3 ( {o rrnorange) to 1.7 (for red) in the first four gr oups. For yel l ow II & green 11rnthis parameter has values of 1.8 & 1.9,respectively . These values of nrnremained constant' in the exponential region which extended over about tworndecades of the voltage for most of the diodes.rnc-v result indicated that all the di odes have ab ru pt junct i ons withrnbuilt in potentials of 2.89. 1. 63. 2.04 , 2. 14, 1.92 & 2. 06 eV fo r red.rnorange , yellow I, yellow II, green I & green II. respec t ive l y. Thernlphoto VB V study showed that luminosity (- (photo) t'ias an exponential vol tagerndependence (of the fo rm eqV/rlKT) in the voltage range over wh ich t hernideality factor (n) nea rly remained constant .rnEmlssion intensity peaks were obse r ved for nil the. LEIJa Ilt wavelengthsrn(energies ) of 560 Obi (2.21SeV); 587 nil (2 . 114eV) ; 590 omrn(2 . 10JeV); 662 om (1.874eV); 562 om (2.208eV) and 59) nm (2.092cV)rnfo r g r een 1. yellow t. orange, red. green II and yellow II, respectively.rnSpectra l emission s tudy and band gap meas urements showed that t.he LEllsrnare of Ga (As . P) with the eXceptIon of the orange LED!'J , whtch In sonterncases showed deviations from the va lues of orange Ga (As.P) LEOs,rnRadiative n!:combinations occured [or the red LEDs a t an impurityrnlevel of about 50 MeV and [or green at about 40 MeV from either bandrnedge s . For yellow LElJs the values we r e as high .18 SU meV. An attempt wasrnmade to evaluate efficiency of the ligh t emission fo r the EL diodes .rnLight emission intens ity compari~on revealed red LEDs as t he mo~t intensernfollowed bv green I. the recombinat ion of which might have possib ly beenrnal'isisted by nit rogen i90electronic traps . The small intensity value inrnall the rest of the diodes might be attribured to the absence of t hernisoelectronic trap~.rnNo position shift of the peak emission energy was observed wi thrndiode currents for all the EL diodes .