NOVELTY - Process for treating biomass (100) comprises e.g.: providing initial source of biomass, where the biomass has initial characteristics including e.g. a content of polysaccharide based polymers; providing first pyrolysis device adapted to heat (112) pretreated biomass under controlled conditions; and introducing pretreated biomass into first pyrolysis device, and operating device under conditions suitable to preferentially affect relative content of polysaccharide based polymers, preferably by providing first pyrolysis product having reduced hemicellulose content as compared to original content.    USE - The process is useful for treating biomass which is useful to recover at least one of the bio-products comprising acids, esters, alcohols, ketones, aldehydes, sugars, furans, phenols, lignin and guaiacols (all claimed) or to recover gasses and oils from biomass.    ADVANTAGE - The process: provides an optimal combination of low capital cost, energy balance, yield, scale and scalability, and the ability to be customized for use with various feedstock and under varying conditions; and improves the collection efficiency of the volatiles and reduces the cost of the gas treatment system.    DETAILED DESCRIPTION - Process for treating biomass (100) comprises: (a) providing an initial source of biomass, where the biomass has initial characteristics, including particle size, water content, and content of polysaccharide based polymers; (b) optionally and preferably, pretreating the initial biomass source in order to provide it with desired characteristics; (c) optionally and preferably, drying the initial biomass source to reduce its moisture content, under conditions in which gasses and/or vapors are captured and subjected to at least one process comprising recycling the gas/vapor into the system, in order to facilitate pretreatment of biomass, condensing and recovering the gas/vapor or its components, and venting or otherwise disposing of the gas/vapor; (d) providing a first pyrolysis device adapted to heat (112) the optionally pretreated biomass under controlled conditions; (e) introducing the optionally pretreated biomass into the first pyrolysis device, and operating the device under conditions suitable to preferentially affect the relative content of polysaccharide based polymers, preferably, by providing a first pyrolysis product having reduced hemicellulose content as compared to original content, while retaining the cellulose and lignin content, and driving off volatiles in the form of at least one gas or vapor; (f) obtaining a first pyrolysis product comprising a carbon enriched material having an altered polysaccharide based polymers; (g) providing a second pyrolysis device, adapted to further pyrolyze the first pyrolysis product in order to provide at least one second pyrolysis gas/vapor and byproduct; (h) introducing the first pyrolysis product into the second device, and operating the device under conditions suitable to provide a second pyrolysis product in the form of a solid ash byproduct having reduced carbon content, and drive off volatiles in the form of a gas or vapor; and (i) recovering the gas/vapor from the second device in a manner sufficient to recover at least one commercially useful components from it. INDEPENDENT CLAIMS are also included for:    (1) a system for performing the process;    (2) an intermediate obtained from the process;    (3) a combination of first and second pyrolysis devices, comprising a first device adapted to pyrolyze biomass to a first temperature, and a second device adapted to pyrolyze the biomass to a second temperature, where the biomass is adapted to be transferred from the first to second devices while at or near the first pyrolysis temperature; and    (4) a bio-product provided either using the process or using the system.    DESCRIPTION OF DRAWING(S) - The figure illustrates a schematic representation of the system.    Biomass (100)    Dryer/heater (104)    First pyrolysis unit (106)    Second pyrolysis unit (108)    Heat (112)