Concrete is a heavy waste, which has porous structure. To great extent concrete is safe and biologically inactive. This can make this material be used as a carrier for the biocatalyst. Androst-4-ene-3, 17-dione (AD) and androsta-1,4-diene-3,17-dione (ADD) are important intermediate in synthesis of wide range of pharmaceutical steroids, Cells of bacterial strain isolated from olive mill and identified as Alkalibacterium olivoapovliticus showed a good ability to convert sterols to AD an ADD. The cells of this stain was entrapped within blocks of concrete. Different parameters were investigated to obtain the maximal products. Study of these parameters nearly doubled the AD formation (from about 56% to over 90%) and the ADD production (from about 35% to about 55%). Furthermore, the immobilized cells possessed a good capacity for recycling and withstand all the bioconversion stresses for about ten successive cycles. Absolutely, this is the first time for the concrete to be used in such studies also Alkalibacterium olivoapovliticus is a recent species and this is the first time to be tested with such important biotransformation application.