NOVELTY - System comprises: a first electrochemical cell, which includes a first region, a second region and a separator, where the first region has a cathode with a catholyte comprising carbon dioxide, the second region has an anode with an anolyte; a first reactor, which reacts the M-carboxylate with a hydrogen compound to produce carboxylic acid; a second electrochemical cell; at least one second reactor reacting the halogen; and at least one third reactor reacting the halogenated compound.    USE - The system is useful for co-producing a first product such as glyoxylic acid, glyoxal, glycolic acid, glycolaldehyde, acetic acid, acetaldehyde, ethanol, ethane, ethylene or ethylene glycol, and a second product such as alkene, alkyne, alcohol, aldehyde, ketone, or longer-chain alkane (all claimed).    ADVANTAGE - The system produces two or more products with high selectivity, and allows the carbon dioxide to oxidize organic compounds, which are the source of hydrogen used in the reduction of carbon dioxide thus economically converting carbon dioxide into valuable materials such as fuels and industrial chemicals and storing mitigation of carbon dioxide emissions and conversion of renewable energy into a chemical form for later use.    DETAILED DESCRIPTION - System (100) for co-producing a first product and a second product, comprises: a first electrochemical cell (102A), which includes a first region, a second region and a separator (120) that selectively controls a flow of ions between the regions, where the first region has a cathode (122) with a catholyte comprising carbon dioxide, the second region has an anode with an anolyte of formula (MX) (I), where M-carboxylate is produced in the first region and a halogen is produced in the second region when an electric potential is applied between the anode and the cathode; a first reactor (134), which reacts the M-carboxylate with a hydrogen compound of (HX) (II) to produce carboxylic acid and (I), the (MX) is recycled to an input of the second region of the first electrochemical cell; a second electrochemical cell, where the second electrochemical cell includes a first region, a second region and a separator that selectively controls a flow of ions between the regions, the second region has an anode with an anolyte comprising (II), where at least one of another carboxylic acid, an aldehyde, a ketone, a glycol or an alcohol is produced at the first region of the second electrochemical cell and a halogen is produced in the second region of the second electrochemical cell when an electric potential is applied between the anode and cathode; at least one second reactor reacting the halogen from the second regions of the first and second electrochemical cells with an alkane, aromatic compound, or other carbon compound to produce a halogenated compound and (II), where the (II) is recycled back to the second region of the second electrochemical cell and to the input of the first reactor; and at least one third reactor reacting the halogenated compound to produce at least one of an alkene, alkyne, ketone, alcohol, aldehyde, unsaturated carbon compound, or longer-chain alkane, and (II).    M = cation; and    X = F, Cl, Br or I.    DESCRIPTION OF DRAWING(S) - The figures show a block diagram of a system for co-producing first and second products.    Product co-producing system (100)    First electrochemical cell (102A)    Separator (120)    Cathode (122)    First reactor. (134)