The existence of horse manure around the neighborhood can lead to pollution. This condition is still existed in the Babakan Loa Cimahi settlement. The application of appropriate technology with horse manure can be processed to produce biogas. In addition to horse feces, water hyacinth (Eicchornia crassipes) can be utilized in the production of biogas because it has a large hemicellulose content. The aim of the research is to find out the effect of water hyacinth addition to the volume of biogas generated from horse manure. The research hypothesis shows that there is an effect of water hyacinth addition to the gas volume production. The populations are all horse manures taken from stables in Babakan Loa and water hyacinths on the paddies, while the samples are partially taken from the population with temporary sampling technique. The type of research is quasi-experimental research with one group pre and post test design. Data collection is done by measuring the gas volume produced. The collected data is processed and analyzed using t dependent test. The result shows that the biogas volume produced without the addition of water hyacinth ranged from 0.7 to 3.1 liters, while with addition of water hyacinth ranged from 1.4 to 11.9 liters. There is a significant difference between the volume of biogas without and with the addition of water hyacinth.