diff --git a/CHANGELOG.rst b/CHANGELOG.rst
index 9434bb5..7f02158 100644
--- a/CHANGELOG.rst
+++ b/CHANGELOG.rst
@@ -12,6 +12,7 @@ v2.2.1-dev
 **********
 * Add novel module, **expression**, which analyzes gene expression
   * Add optional input `strandedness` to the sample configuration
+  * Add json output file for the expression module
 
 **********
 v2.1.3
diff --git a/includes/expression/Snakefile b/includes/expression/Snakefile
index cc9165b..0d9199e 100644
--- a/includes/expression/Snakefile
+++ b/includes/expression/Snakefile
@@ -5,6 +5,7 @@ rule all:
     input:
         multiqc="multiqc_expression.html",
         seamless=[f"{sample.sample}/expression/seAMLess.tsv" for sample in samples],
+        json=[module_output.json(sample) for sample in samples],
 
 
 rule normalized_coverage:
@@ -74,6 +75,30 @@ rule transform_counts:
         """
 
 
+rule json_output:
+    input:
+        coverage=module_output.normalized_expression,
+        src=srcdir("scripts/json-output.py"),
+    params:
+        strandedness=get_strand,
+        genes=config["report"],
+    output:
+        "{sample}/expression/expression-output.json",
+    log:
+        "log/expression.{sample}.txt",
+    container:
+        containers["pysam"]
+    shell:
+        """
+        python3 {input.src} \
+            --coverage {input.coverage} \
+            --strandedness {params.strandedness} \
+            --genes {params.genes} \
+            --sample {wildcards.sample} \
+            > {output} 2> {log}
+        """
+
+
 rule merge_samples:
     input:
         counts=[module_output.normalized_expression(sample) for sample in samples],
diff --git a/includes/expression/common.smk b/includes/expression/common.smk
index 4eafe96..af65ef9 100644
--- a/includes/expression/common.smk
+++ b/includes/expression/common.smk
@@ -43,6 +43,11 @@ def set_housekeeping_genes():
     config["housekeeping"] = str_to_list(housekeeping)
 
 
+def set_pdf_report_genes():
+    report_genes = config.get("report")
+    config["report"] = str_to_list(report_genes)
+
+
 ## Input functions ##
 def get_bam(wildcards):
     return pep.sample_table.loc[wildcards.sample, "bam"]
@@ -79,17 +84,23 @@ def check_housekeeping():
             raise RuntimeError(msg)
 
 
-def check_bed_genes_of_interest():
-    """Check for duplicates genes bed file and genes_of_interest"""
+def _bed_names():
+    """Get gene names from the Bed file"""
     if "bed" not in config:
-        return
+        return list()
 
-    # Get the names from the bed file
     names = list()
     with open(config["bed"]) as fin:
         for line in fin:
             spline = line.strip("\n").split("\t")
             names.append(spline[3])
+    return names
+
+
+def check_bed_genes_of_interest():
+    """Check for duplicates genes bed file and genes_of_interest"""
+    # Get the names from the bed file
+    names = _bed_names()
 
     for gene in config["genes_of_interest"]:
         if gene in names:
@@ -97,6 +108,14 @@ def check_bed_genes_of_interest():
             raise RuntimeError(msg)
 
 
+def check_genes_for_report():
+    quantified_genes = _bed_names() + config["genes_of_interest"]
+    for gene in config["report"]:
+        if gene not in quantified_genes:
+            msg = f"{gene} is specified for the report, but not in genes_of_interest or the bed file"
+            raise RuntimeError(msg)
+
+
 ## Functions for module outputs ##
 def coverage(wildcards):
     return f"{wildcards.sample}/expression/coverage.csv"
@@ -113,11 +132,23 @@ def multiqc_files():
     return unstranded + stranded
 
 
+def get_json(wildcards):
+    return f"{wildcards.sample}/expression/expression-output.json"
+
+
+# Set default values, parse specified values
 set_genes_of_interest()
 set_housekeeping_genes()
+set_pdf_report_genes()
+
+# Check the sanity of the reported settings
 check_housekeeping()
 check_bed_genes_of_interest()
+check_genes_for_report()
 
 module_output = SimpleNamespace(
-    coverage=coverage, normalized_expression=normalized, multiqc_files=multiqc_files()
+    coverage=coverage,
+    normalized_expression=normalized,
+    multiqc_files=multiqc_files(),
+    json=get_json,
 )
diff --git a/includes/expression/scripts/json-output.py b/includes/expression/scripts/json-output.py
new file mode 100755
index 0000000..6caed34
--- /dev/null
+++ b/includes/expression/scripts/json-output.py
@@ -0,0 +1,46 @@
+#!/usr/bin/env python
+
+import json
+import argparse
+import os
+
+from multiqc import read_expression
+
+def fusion_results(fname):
+    # Initialise the results dictionary
+    with open(fname) as fin:
+        return json.load(fin)
+
+def main(args):
+    """ Create json output of expression results """
+    
+    # Create results dictionary
+    results = {
+            "metadata": {
+                "sample_name": args.sample
+            },
+            "genes": dict()
+    }
+    
+    # Read the normalized expression for the specified strand
+    expression = read_expression(args.coverage, args.strandedness)
+
+    # Extract the genes of interest
+    genes = dict()
+    for gene in args.genes:
+        genes[gene] = expression[gene]
+
+    results["genes"] = genes
+    print(json.dumps({"expression": results}, sort_keys=True, indent=2))
+
+
+if __name__ == "__main__":
+    parser = argparse.ArgumentParser()
+    parser.add_argument('--coverage', help='Normalized coverage file')
+    parser.add_argument('--sample', help = 'Sample name')
+    parser.add_argument('--strandedness', help='Strandedness of the sample')
+    parser.add_argument('--genes', nargs='*', default=list(), help='genes to include')
+
+    args = parser.parse_args()
+    main(args)
+
diff --git a/test/test_expression.yml b/test/test_expression.yml
index 69f3f16..c528fa0 100644
--- a/test/test_expression.yml
+++ b/test/test_expression.yml
@@ -13,6 +13,7 @@
     contains:
       - "rule merge_samples"
       - "rule transform_counts"
+      - "rule json_output"
 
 - name: Test error on unknown housekeeping gene
   tags:
@@ -62,6 +63,7 @@
     --config
       pepfile=test/pep/expression.csv
       bed=test/data/reference/transcripts_chrM.bed
+      report="MT-ND4 MT-TH"
   exit_code: 0
   files:
     - path: SRR8615409/expression/coverage.csv
@@ -94,6 +96,10 @@
     - path: multiqc_expression.html
       contains:
         - "MT-CO2"
+    - path: SRR8615409/expression/expression-output.json
+      contains:
+        - "MT-ND4"
+        - "MT-TH"
 
 - name: Run the expression module with genes of interest
   tags:
@@ -106,7 +112,7 @@
     --configfile test/data/config/expression.json
     --config
       pepfile=test/pep/expression.csv
-      genes_of_interest="MT-CO2"
+      genes_of_interest="MT-CO2 MT-ND4 MT-TH"
   exit_code: 0
   files:
     - path: SRR8615409/expression/coverage.csv
@@ -126,6 +132,7 @@
   tags:
     - functional
     - expression
+    - current
   command: >
     snakemake
     --snakefile includes/expression/Snakefile