Aerosol measurements are conducted in several applications, such as in air quality and emission analysis. This thesis focuses on electrical aerosol instrumentation, in which the aerosol detection is achieved by measuring electric current from charged particles. If particle charge is known accurately, the current produced by particles can be used as an accurate and traceable concentration reference in calibration of various aerosol instruments. Additionally, same methods can be applied with small modifications in the measurement of particle charge. These form the main objectives of this thesis, which are to develop particle charge measurement and aerosol instrument calibration methods in a size range from nanometers to micrometers.<br /><br />In this thesis, the operation of the Electrical Low Pressure Impactor (ELPI+) is introduced. The instrument contains two main components, charger and impactor, which were characterized in calibration measurements. The ELPI+ and the Differential Mobility Analyzer (DMA) were used as a basis of the developed DMA-ELPI particle charge measurement method, in which particles are classified according to their electrical mobility, which is a function of particle size and charge. This is followed by aerodynamic size classification and detection with an ELPI+. The main advantage of the developed method is the wide particle size range compared to other available techniques. The charge measurement was successfully tested using particles with well-defined size distributions and charging states. Additionally, an instrument called BOLAR was developed for studying charge from inhaler-generated particles. The BOLAR is capable of measuring the size fractioned bipolar charging state of aerosol particles. The operation of the instrument was verified with calibration measurements, and the instrument was applied in studying charge of inhaler-generated particles. As a final application of electrical aerosol instrumentation, a new wide size range instrument calibration setup was developed. This included designing and constructing a particle growth unit, an electrical mobility classifier for μm-sized particles and a flow mixing and splitting assembly. All these components were characterized, and the setup was used to calibrate a particle counter traceably in the size range from 3.6 nm to 5.3 μm, which has not previously been possible with any single setup. The introduced high accuracy calibration method can be used as a traceable primary standard for particle number concentration.