This thesis work is mainly focused on improving Ethiopian indigenous ethanol (“areki”) processing technology. The effect of mashing and fermentation on the quality of wort and distillery beer was examined using response surface methodology. The preliminary investigation contains five trial experiments and was conducted at the following conditions: trial experiment “A‟ was done by using pure traditional production process, and it gave 22.5 % of malt extract and 2.7 oBx of sugar content from barley sourced a place known as jiga, trial experiment “B‟ was studied at temperature of 40, 55, 70 oC, pH value of 4.5, 5.5, 6.5, and time of 120, 180, 240 min using traditional malt. It showed that at the combination factors of 55 oC, 180 min and pH value of 5.5, there were maximum % extract of 37.35 % and sugar content of 4.5 oBx. Trial experiment “C‟ was conducted at the same temperature, pH, and time as trial experiment “B‟, but substrate source added of 15, 22.5, 30 gm was considered additionally using traditional malt. It showed that at the combination factors of 55 oC, 180 min, pH value of 5.5, and substrate source added of 22.5 gm, there maximum % extract of 40.5 % and sugar content of 4.8 oBx. Trial experiment “D‟, was studied by considering factors which were considered in trial experiment “B‟, but commercial malt was used instead of traditional malt, and the best result % extract of 50.85 % and 6.1oBx sugar content were observed. Similarly for the final trial experiment “E‟ all the factors and their value were the same as trial experiment “C‟, but commercial malt was used instead of traditional malt, and the best % extract of 70.10 % and sugar content of 8.4 oBx were obtained. The maximum % malt extract (92.36 %) and fermentable sugar (10.53 oBx) was observed at 70oC, 120 min., pH value of 4.5 and 30 gm substrate source addition. After optimizing the wort, the fermentation experiment was conducted accordingly the combination which was given by design expert software. The maximum degree of attenuation value (86 %) was observed at 20oC, 96 hr, and pH value of 4.4 and 75 gm substrate source added. The maximum alcoholic strength of 80.2 % v/v (160.4 proof) was recorded for 86 % maximum degree of attenuation sample. Therefore, good barley type and optimum condition for mashing and fermentation process were found to be significant for high wort, distillery beer and alcohol quality.