To improve the separation of dispersedly precipitated sulfur from a washing solution used in the oxidative washing of hydrogen sulfide containing waste gases, the suspension is heated before filtration to about 45.degree. C. to 70.degree. C. Such heating causes the sulfur contained in the solution to coagulate into large flocks and form a mass of high purity sulfur which is largely non-thixotropic. This mass, often called a filter cake, can be washed and utilized in a large number of ways as a source of sulfur.