ISO 18135:2017 describes methods for preparing sampling plans and certificates, as well as taking samples of solid biofuels, for example, from the place where the raw materials grow, from production plant, from deliveries, e.g. lorry loads, or from stock. It includes both manual and mechanical methods, and is applicable to solid biofuels that are either:- fine (particle sizes up to about 10 mm) and regularly shaped particulate materials that can be sampled using a scoop or pipe, for example, sawdust, olive stones and wood pellets;- coarse or irregularly shaped particulate materials (particle sizes up to about 200 mm) that can be sampled using a fork or shovel, for example, wood chips and nut shells, forest residue chips, and straw;- baled materials, for example, baled straw or grass;- large pieces (particle sizes above 200 mm) that are either picked manually or automatically;- vegetable waste, fibrous waste from virgin pulp production and from production of paper from pulp that has been dewatered;- thermally treated and densified biomass materials;- roundwood.ISO 18135:2017 is not applicable to airborne dust from solid biofuels. It may be possible to use this document for other solid biofuels.The methods described in this document may be used, for example, when the samples are to be tested for moisture content, ash content, calorific value, bulk density, durability, particle size distribution, ash melting behaviour and chemical composition.