Microbial biofilms are behind microbiologically influenced corrosion (MIC). Currently, all the so-called MIC test kits on the market are actually microbe test kits. Our new disposable miniature electrochemical biofilm/MIC test kit based on 10 ml serum vials with solid-state electrodes fills the gap to provide corrosion information such as abiotic corrosion vs. MIC, and MIC by electron-harvesting biofilms vs. MIC by corrosive metabolites. It can also test antimicrobial efficacy. An electrochemical workstation is used as a base station to perform various electrochemical scans such as linear polarization resistance, electrochemical impedance spectrometry and potentiodynamic polarization scans to provide near-real time transient corrosion data after a fluid or sludge is injected into the vial. This work presented a prototype with two different solid-state electrode choices. Three different methods to distinguish MIC from abiotic corrosion, and two different methods to distinguish MIC by electron-harvesting biofilms from MIC by corrosive metabolites. Anaerobic Desulfovibrio ferrophilus IS5 (a highly corrosive sulfate reducing bacterium) biofilm, aerobic Pseudomonas aeruginosa biofilm and an anaerobic corrosive oilfield biofilm consortium were used as examples. Tetrakis hydroxymethyl phosphonium sulfate (THPS) biocide was used as an example for assessing biocide efficacy. The patent-pending technology is currently undergoing field-testing.